Tampermonkey®
by Jan Biniok
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Table of Contents

Userscript Header
@name

The name of the script.

Internationalization is done by adding an appendix naming the locale.

// @name    A test
// @name:de Ein Test

@namespace

The namespace of the script.
@copyright

A copyright statement shown at the header of the script's editor right below the script name.
@version

The script version. This is used for the update check and needs to be increased at every update.

In this list the next entry is considered to be a higher version number, eg: Alpha-v1 < Alpha-v2 and 16.4 == 16.04

    Alpha-v1
    Alpha-v2
    Alpha-v10
    Beta
    0.5pre3
    0.5prelimiary
    0.6pre4
    0.6pre5
    0.7pre4
    0.7pre10
    1.-1
    1 == 1. == 1.0 == 1.0.0
    1.1a
    1.1aa
    1.1ab
    1.1b
    1.1c
    1.1.-1
    1.1 == 1.1.0 == 1.1.00
    1.1.1.1.1
    1.1.1.1.2
    1.1.1.1
    1.10.0-alpha
    1.10 == 1.10.0
    1.11.0-0.3.7
    1.11.0-alpha
    1.11.0-alpha.1
    1.11.0-alpha+1
    1.12+1 == 1.12+1.0
    1.12+1.1 == 1.12+1.1.0
    1.12+2
    1.12+2.1
    1.12+3
    1.12+4
    1.12
    2.0
    16.4 == 16.04
    2023-08-17.alpha
    2023-08-17
    2023-08-17_14-04 == 2023-08-17_14-04.0
    2023-08-17+alpha
    2023-09-11_14-0

@description

A short significant description.

Internationalization is done by adding an appendix naming the locale.

// @description    This userscript does wonderful things
// @description:de Dieses Userscript tut wundervolle Dinge

@icon, @iconURL, @defaulticon

The script icon in low res.
@icon64, @icon64URL

This scripts icon in 64x64 pixels. If this tag, but @icon is given the @icon image will be scaled at some places at the options page.
@grant

@grant is used to whitelist GM_* and GM.* functions, the unsafeWindow object and some powerful window functions.

// @grant GM_setValue
// @grant GM_getValue
// @grant GM.setValue
// @grant GM.getValue
// @grant GM_setClipboard
// @grant unsafeWindow
// @grant window.close
// @grant window.focus
// @grant window.onurlchange

Since closing and focusing tabs is a powerful feature this needs to be added to the @grant statements as well. In case @grant is followed by none the sandbox is disabled. In this mode no GM_* function but the GM_info property will be available.

// @grant none

If no @grant tag is given an empty list is assumed. However this different from using none.
@author

The scripts author.
@homepage, @homepageURL, @website, @source

The authors homepage that is used at the options page to link from the scripts name to the given page. Please note that if the @namespace tag starts with http:// its content will be used for this too.
@antifeature

This tag allows script developers to disclose whether they monetize their scripts. It is for example required by GreasyFork.

Syntax: <tag> <type> <description>

<type> can have the following values:

    ads
    tracking
    miner

// @antifeature       ads         We show you ads
// @antifeature:fr    ads         Nous vous montrons des publicités
// @antifeature       tracking    We have some sort of analytics included
// @antifeature       miner       We use your computer's resources to mine a crypto currency

Internationalization is done by adding an appendix naming the locale.
@require

Points to a JavaScript file that is loaded and executed before the script itself starts running. Note: the scripts loaded via @require and their "use strict" statements might influence the userscript's strict mode!

// @require https://code.jquery.com/jquery-2.1.4.min.js
// @require https://code.jquery.com/jquery-2.1.3.min.js#sha256=23456...
// @require https://code.jquery.com/jquery-2.1.2.min.js#md5=34567...,sha256=6789...
// @require tampermonkey://vendor/jquery.js
// @require tampermonkey://vendor/jszip/jszip.js

Please check the sub-resource integrity section for more information how to ensure integrity.

Multiple tag instances are allowed.
@resource

Preloads resources that can by accessed via GM_getResourceURL and GM_getResourceText by the script.

// @resource icon1       http://www.tampermonkey.net/favicon.ico
// @resource icon2       /images/icon.png
// @resource html        http://www.tampermonkey.net/index.html
// @resource xml         http://www.tampermonkey.net/crx/tampermonkey.xml
// @resource SRIsecured1 http://www.tampermonkey.net/favicon.ico#md5=123434...
// @resource SRIsecured2 http://www.tampermonkey.net/favicon.ico#md5=123434...;sha256=234234...

Please check the sub-resource integrity section for more information how to ensure integrity.

Multiple tag instances are allowed.
@include

The pages on that a script should run. Multiple tag instances are allowed. @include doesn't support the URL hash parameter. You have to match the path without the hash parameter and make use of window.onurlchange

// @include http://www.tampermonkey.net/*
// @include http://*
// @include https://*
// @include /^https:\/\/www\.tampermonkey\.net\/.*$/
// @include *

Note: When writing something like *://tmnk.net/* many script developers expect the script to run at tmnk.net only, but this is not the case. It also runs at https://example.com/?http://tmnk.net/ as well.

Therefore Tampermonkey interprets @includes that contain a :// a little bit like @match. Every * before :// only matches everything except : characters to makes sure only the URL scheme is matched. Also, if such an @include contains a / after ://, then everything between those strings is treat as host, matching everything except / characters. The same applies to * directly following ://.

@match

In Tampermonkey, the @match directive is used to specify the web pages that your script should run on. The value of @match should be a URL pattern that matches the pages you want your script to run on. Here are the parts of the URL pattern that you'll need to set:

// @match <protocol>://<domain><path>

    protocol - This is the first part of the URL, before the colon. It specifies the protocol that the page uses, such as http or https. * matches both.
    domain - This is the second part of the URL, after the protocol and two slashes. It specifies the domain name of the website, such as tmnk.com. You can use the wildcard character this way *.tmnk.net to match tmnk.net and any sub-domain of it like www.tmnk.net.
    path - This is the part of the URL that comes after the domain name, and may include additional subdirectories or filenames. You can use the wildcard character * to match any part of the path.

Please check this documentation to get more information about match pattern. Note: the <all_urls> statement is not yet supported and the scheme part also accepts http*://.

Multiple tag instances are allowed.

More examples:

// @match *://*/*
// @match https://*/*
// @match http://*/foo*
// @match https://*.tampermonkey.net/foo*bar

@exclude

Exclude URLs even it they are included by @include or @match.

Multiple tag instances are allowed.
@run-at

Defines the moment the script is injected. In opposition to other script handlers, @run-at defines the first possible moment a script wants to run. This means it may happen, that a script that uses the @require tag may be executed after the document is already loaded, cause fetching the required script took that long. Anyhow, all DOMNodeInserted and DOMContentLoaded events that happended after the given injection moment are cached and delivered to the script when it is injected.

// @run-at document-start

The script will be injected as fast as possible.

// @run-at document-body

The script will be injected if the body element exists.

// @run-at document-end

The script will be injected when or after the DOMContentLoaded event was dispatched.

// @run-at document-idle

The script will be injected after the DOMContentLoaded event was dispatched. This is the default value if no @run-at tag is given.

// @run-at context-menu

The script will be injected if it is clicked at the browser context menu. Note: all @include and @exclude statements will be ignored if this value is used, but this may change in the future.
@sandbox

@sandbox allows Tampermonkey to decide where the userscript is injected:

    MAIN_WORLD - the page
    ISOLATED_WORLD - the extension's content script
    USERSCRIPT_WORLD - a special context created for userscripts

But instead of specifying an environment, the userscript can express what exactly it needs access to. @sandbox supports three possible arguments:

    raw "Raw" access means that a script for compatibility reasons always needs to run in page context, the MAIN_WORLD. At the moment this mode is the default if @sandbox is omitted. If injection into the MAIN_WORLD is not possible (e.g. because of a CSP) the userscript will be injected into other (enabled) sandboxes according to the order of this list.

    JavaScript "JavaScript" access mode means that this script needs access to unsafeWindow. At Firefox a special context, the USERSCRIPT_WORLD, is created which also bypasses existing CSPs. It however, might create new issues since now cloneInto and exportFunction are necessary to share objects with the page. raw mode is used as fallback at other browsers.

    DOM Use this access mode if the script only needs DOM and no direct unsafeWindow access. If enabled these scripts are executed inside the extension context, the ISOLATED_WORLD, or at any other enabled context otherwise, because they all grant DOM access.

// @sandbox JavaScript

@connect

This tag defines the domains (no top-level domains) including subdomains which are allowed to be retrieved by GM_xmlhttpRequest

// @connect <value>

<value> can be:

    a domain name like example.com (this will also allow all subdomains).
    a subdomain name like subdomain.example.com.
    self to whitelist the domain the script is currently running at.
    localhost to access the localhost.
    an IP address like 1.2.3.4.
    *.

If it's not possible to declare all domains a userscript might connect to then it's a good practice to do the following:

    Declare all known or at least all common domains that might be connected by the script to avoid the confirmation dialog for most users.
    Additionally add @connect * to the script to allow Tampermonkey to offer an "Always allow all domains" button.

Users can also whitelist all requests by adding * to the user domain whitelist at the script settings tab.

Notes:

    Both, the initial and the final URL will be checked!
    For backward compatibility to Scriptish @domain tags are interpreted as well.
    Multiple tag instances are allowed.

More examples:

// @connect tmnk.net
// @connect www.tampermonkey.net
// @connect self
// @connect localhost
// @connect 8.8.8.8
// @connect *

@noframes

This tag makes the script running on the main pages, but not at iframes.
@updateURL

An update URL for the userscript. Note: a @version tag is required to make update checks work.
@downloadURL

Defines the URL where the script will be downloaded from when an update was detected. If the value none is used, then no update check will be done.
@supportURL

Defines the URL where the user can report issues and get personal support.
@webRequest

@webRequest takes a JSON document that matches GM_webRequest's rule parameter. It allows the rules to apply even before the userscript is loaded.
@unwrap

Injects the userscript without any wrapper and sandbox into the page, which might be useful for Scriptlets.
Application Programming Interface
unsafeWindow

The unsafeWindow object provides access to the window object of the page that Tampermonkey is running on, rather than the window object of the Tampermonkey extension. This can be useful in some cases, such as when a userscript needs to access a JavaScript library or variable that is defined on the page.
Subresource Integrity

Subresource Integrity (SRI) is a security feature that allows userscript developers to ensure that the external resources (such as JavaScript libraries and CSS files) that they include in their userscript have not been tampered with or modified. This is accomplished by generating a cryptographic hash of the resource and including it in @require and @resource tags. When the userscript is installed, Tampermonkey will calculate the hash of the resource and compare it to the included hash. If the two hashes do not match, Tampermonkey will refuse to load the resource, preventing attackers from injecting malicious code into your userscript.

The hash component of the URL of @resource and @require tags is used for this purpose.

// @resource SRIsecured1 http://example.com/favicon1.ico#md5=ad34bb...
// @resource SRIsecured2 http://example.com/favicon2.ico#md5=ac3434...,sha256=23fd34...
// @require              https://code.jquery.com/jquery-2.1.1.min.js#md5=45eef...
// @require              https://code.jquery.com/jquery-2.1.2.min.js#md5-ac56d...,sha256-6e789...
// @require              https://code.jquery.com/jquery-3.6.0.min.js#sha256-/xUj+3OJU...ogEvDej/m4=

Tampermonkey supports SHA-256 and MD5 hashes natively, all other (SHA-1, SHA-384 and SHA-512) depend on window.crypto.

In case multiple hashes (separated by comma or semicolon) are given the last currently supported one is used by Tampermonkey. All hashes need to be encoded in either hex or Base64 format.
GM_addElement(tag_name, attributes), GM_addElement(parent_node, tag_name, attributes)

GM_addElement allows Tampermonkey scripts to add new elements to the page that Tampermonkey is running on. This can be useful for a variety of purposes, such as adding script and img tags if the page limits these elements with a content security policy (CSP).

It creates an HTML element specified by "tag_name" and applies all given "attributes" and returns the injected HTML element. If a "parent_node" is given, then it is attached to it or to document head or body otherwise.

For suitable "attributes", please consult the appropriate documentation. For example:

    script tag
    img tag
    style tag

GM_addElement('script', {
  textContent: 'window.foo = "bar";'
});

GM_addElement('script', {
  src: 'https://example.com/script.js',
  type: 'text/javascript'
});

GM_addElement(document.getElementsByTagName('div')[0], 'img', {
  src: 'https://example.com/image.png'
});

GM_addElement(shadowDOM, 'style', {
  textContent: 'div { color: black; };'
});

Note: this feature is experimental and the API may change.
GM_addStyle(css)

Adds the given style to the document and returns the injected style element.
GM_download(details), GM_download(url, name)

GM_download allows userscripts to download a file from a specified URL and save it to the user's local machine.

The GM_download function takes the following parameters:

details can have the following attributes:

    url: The URL of the file to download. This must be a valid URL and must point to a file that is accessible to the user.
    name: The name to use for the downloaded file. This should include the file's extension, such as .txt or .pdf. For security reasons the file extension needs to be whitelisted at Tampermonkey's options page
    headers: An object containing HTTP headers to include in the download request. See GM_xmlhttpRequest for more details.
    saveAs: A boolean value indicating whether to use the user's default download location, or to prompt the user to choose a different location. This option works in browser API mode only.
    conflictAction: A string that control what happens when a file with this name already exists. This option works in browser API mode only. Possible values are uniquify, overwrite and prompt. Please check this link for more details.
    onload: A function to call when the download has completed successfully.
    onerror: A function to call if the download fails or is cancelled.
    onprogress A callback to be executed if this download made some progress.
    ontimeout A callback to be executed if this download failed due to a timeout.

The download argument of the onerror callback can have the following attributes:

    error: error reason
        not_enabled - the download feature isn't enabled by the user
        not_whitelisted - the requested file extension is not whitelisted
        not_permitted - the user enabled the download feature, but did not give the downloads permission
        not_supported - the download feature isn't supported by the browser/version
        not_succeeded - the download wasn't started or failed, the details attribute may provide more information
    details: detail about that error

Returns an object with the following property:

    abort: A function which can be called to cancel this download.

If GM.download is used it returns a promise that resolves to the download details and also has an abort function.

Depending on the download mode GM_info provides a property called downloadMode which is set to one of the following values: native, disabled or browser.

GM_download("http://example.com/file.txt", "file.txt");

const download = GM_download({
    url: "http://example.com/file.txt",
    name: "file.txt",
    saveAs: true
});

// cancel download after 5 seconds
window.setTimeout(() => download.abort(), 5000);

Note: The browser might modify the desired filename. Especially a file extension might be added if the browser finds this to be safe to download at the current OS.
GM_getResourceText(name)

Allows userscripts to access the text of a resource (such as a JavaScript or CSS file) that has been included in a userscript via @resource.

The function takes a single parameter, which is the "name" of the resource to retrieve. It returns the text of the resource as a string.

Here is an example of how the function might be used:

const scriptText = GM_getResourceText("myscript.js");
const scriptText2 = await GM.getResourceText("myscript.js");
const script = document.createElement("script");
script.textContent = scriptText;
document.body.appendChild(script);

GM_getResourceURL(name)

GM_getResourceURL allows userscripts to access the URL of a resource (such as a CSS or image file) that has been included in the userscript via a @resource tag at the script header.

The function takes a single parameter, which is the "name" of the resource to retrieve. It returns the URL of the resource as a string.

const imageUrl = GM_getResourceURL("myimage.png");
const imageUrl2 = await GM.getResourceURL("myimage.png");
const image = document.createElement("img");
image.src = imageUrl;
document.body.appendChild(image);

GM_info

Get some info about the script and TM. The object might look like this:

type ScriptGetInfo = {
    downloadMode: string,
    isFirstPartyIsolation?: boolean,
    isIncognito: boolean,
    sandboxMode: SandboxMode,
    scriptHandler: string,
    scriptMetaStr: string | null,
    scriptUpdateURL: string | null,
    scriptWillUpdate: boolean,
    version?: string,
    script: {
        antifeatures: { [antifeature: string]: { [locale: string]: string } },
        author: string | null,
        blockers: string[],
        connects: string[],
        copyright: string | null,
        deleted?: number | undefined,
        description_i18n: { [locale: string]: string } | null,
        description: string,
        downloadURL: string | null,
        excludes: string[],
        fileURL: string | null,
        grant: string[],
        header: string | null,
        homepage: string | null,
        icon: string | null,
        icon64: string | null,
        includes: string[],
        lastModified: number,
        matches: string[],
        name_i18n: { [locale: string]: string } | null,
        name: string,
        namespace: string | null,
        position: number,
        resources: Resource[],
        supportURL: string | null,
        system?: boolean | undefined,
        'run-at': string | null,
        unwrap: boolean | null,
        updateURL: string | null,
        version: string,
        webRequest: WebRequestRule[] | null,
        options: {
            check_for_updates: boolean,
            comment: string | null,
            compatopts_for_requires: boolean,
            compat_wrappedjsobject: boolean,
            compat_metadata: boolean,
            compat_foreach: boolean,
            compat_powerful_this: boolean | null,
            sandbox: string | null,
            noframes: boolean | null,
            unwrap: boolean | null,
            run_at: string | null,
            tab_types: string | null,
            override: {
                use_includes: string[],
                orig_includes: string[],
                merge_includes: boolean,
                use_matches: string[],
                orig_matches: string[],
                merge_matches: boolean,
                use_excludes: string[],
                orig_excludes: string[],
                merge_excludes: boolean,
                use_connects: string[],
                orig_connects: string[],
                merge_connects: boolean,
                use_blockers: string[],
                orig_run_at: string | null,
                orig_noframes: boolean | null
            }
        }
    }
};

type SandboxMode = 'js' | 'raw' | 'dom';

type Resource = {
    name: string,
    url: string,
    error?: string,
    content?: string,
    meta?: string
};

type WebRequestRule = {
    selector: { include?: string | string[], match?: string | string[], exclude?: string | string[] } | string,
    action: string | {
        cancel?: boolean,
        redirect?: {
            url: string,
            from?: string,
            to?: string
        } | string
    }
};

GM_log(message)

Log a message to the console.
GM_notification(details, ondone), GM_notification(text, title, image, onclick)

GM_notification allows users to display notifications on the screen, using a provided message and other optional parameters.

The function takes several parameters. Either a details object or multiple parameters.

The details object can have the following attributes, from which some can also be used as direct parameter.

The available options include:

    text: A string containing the message to display in the notification.
    title: The title of the notification.
    tag: v5.0+ This tag will be used to identify this notification. This way you can update existing notifications by calling GM_notification again and using the same tag. If you don't provide a tag, a new notification will be created every time.
    image: The URL of an image to display in the notification.
    highlight: A boolean flag whether to highlight the tab that sends the notfication (required unless text is set)
    silent: A boolean flag whether to not play a sound
    timeout: The time, in milliseconds, after which the notification should automatically close.
    url: v5.0+ A URL to load when the user clicks on the notification. You can prevent loading the URL by calling event.preventDefault() in the onclick event handler.
    onclick: A callback function that will be called when the user clicks on the notification.
    ondone A callback function that will be called when the notification is closed (no matter if this was triggered by a timeout or a click) or the tab was highlighted

The function does not return a value.

If no url and no tag is provided the notification will closed when the userscript unloads v5.0+(e.g. when the page is reloaded or the tab is closed).

Here is an example of how the function might be used:

GM_notification({
  text: "This is the notification message.",
  title: "Notification Title",
  url: 'https:/example.com/',
  onclick: (event) => {
    // The userscript is still running, so don't open example.com
    event.preventDefault();
    // Display an alert message instead
    alert('I was clicked!')
  }
});

const clicked = await GM.notification({ text: "Click me." });

GM_openInTab(url, options), GM_openInTab(url, loadInBackground)

GM_openInTab allows userscripts to open a new tab in the browser and navigate to a specified URL.

The function takes two parameters:

A string names "url" containing the URL of the page to open in the new tab.

An optional options object that can be used to customize the behavior of the new tab. The available options include:

    active: A boolean value indicating whether the new tab should be active (selected) or not. The default is false.
    insert: An integer indicating the position at which the new tab should be inserted in the tab strip. The default is false, which means the new tab will be added to the end of the tab strip.
    setParent: A boolean value indicating whether the new tab should be considered a child of the current tab. The default is false.
    incognito A boolean value that makes the tab being opened inside a incognito mode/private mode window.
    loadInBackground A boolean value has the opposite meaning of active and was added to achieve Greasemonkey 3.x compatibility.

The function returns an object with the function close, the listener onclose and a flag called closed.

Here is an example of how the function might be used:

// Open a new tab and navigate to the specified URL
GM_openInTab("https://www.example.com/");

GM_registerMenuCommand(name, callback, options_or_accessKey)

GM_registerMenuCommand allows userscripts to add a new entry to the userscript's menu in the browser, and specify a function to be called when the menu item is selected.

The function takes three parameters:

    name - string, A string containing the text to display for the menu item.
    callback - function, A function to be called when the menu item is selected. The function will be passed a single parameter, which is the currently active tab. As of Tampermonkey 4.14 a MouseEvent or KeyboardEvent is passed as function argument.
    accessKey - string?, An optional access key. Please see the description below. Either options or accessKey can be specified.
    options v4.20+ object?, Optional options that can be used to customize the menu item. The options are specified as an object with the following properties:
        id v5.0+ number|string?, An optional number that was returned by a previous GM_registerMenuCommand call. If specified, the according menu item will be updated with the new options. If not specified or the menu item can't be found, a new menu item will be created.
        accessKey - string?, An optional access key for the menu item. This can be used to create a shortcut for the menu item. For example, if the access key is "s", the user can select the menu item by pressing "s" when Tampermonkey's popup-menu is open. Please note that there are browser-wide shortcuts configurable to open Tampermonkey's popup-menu.
        autoClose - boolean?, An optional boolean parameter that specifies whether the popup menu should be closed after the menu item is clicked. The default value is true. Please note that this setting has no effect on the menu command section that is added to the page's context menu.
        title v5.0+ - string?, An optional string that specifies the title of the menu item. This is displayed as a tooltip when the user hovers the mouse over the menu item.

The function return a menu entry ID that can be used to unregister the command.

Here is an example of how the function might be used:

const menu_command_id_1 = GM_registerMenuCommand("Show Alert", function(event: MouseEvent | KeyboardEvent) {
  alert("Menu item selected");
}, {
  accessKey: "a",
  autoClose: true
});

const menu_command_id_2 = GM_registerMenuCommand("Log", function(event: MouseEvent | KeyboardEvent) {
  console.log("Menu item selected");
}, "l");

GM_unregisterMenuCommand(menuCmdId)

GM_unregisterMenuCommand removes an existing entry from the userscript's menu in the browser.

The function takes a single parameter, which is the ID of the menu item to remove. It does not return a value.

Here is an example of how the function might be used:

const menu_command_id = GM_registerMenuCommand(...);
GM_unregisterMenuCommand(menu_command_id);

GM_setClipboard(data, info, cb)

GM_setClipboard sets the text of the clipboard to a specified value.

The function takes a parameter "data", which is the string to set as the clipboard text, a parameter "info" and an optional callback function "cb".

"info" can be just a string expressing the type text or html or an object like "cb" is an optional callback function that is called when the clipboard has been set.

{
    type: 'text',
    mimetype: 'text/plain'
}

GM_setClipboard("This is the clipboard text.", "text", () => console.log("Clipboard set!"));
await GM.setClipboard("This is the newer clipboard text.", "text");
console.log('Clipboard set again!');

GM_getTab(callback)

The GM_getTab function takes a single parameter, a callback function that will be called with an object that is persistent as long as this tab is open.

GM_getTab((tab) => console.log(tab));
const t = await GM.getTab();
console.log(t);

GM_saveTab(tab, cb)

The GM_saveTab function allows a userscript to save information about a tab for later use.

The function takes a "tab" parameter, which is an object containing the information to be saved about the tab and an optional callback function "cb".

The GM_saveTab function saves the provided tab information, so that it can be retrieved later using the GM_getTab function.

Here is an example of how the GM_saveTab function might be used in a userscript:

GM_getTab(function(tab) {
    tab.newInfo = "new!";
    GM_saveTab(tab);
});
await GM.saveTab(tab);

In this example, the GM_saveTab function is called with the tab object returned by the GM_getTab function, and a new key called "newInfo".
GM_getTabs(callback)

The GM_getTabs function takes a single parameter: a callback function that will be called with the information about the tabs.

The "tabs" object that is passed to the callback function contains objects, with each object representing the saved tab information stored by GM_saveTab.

GM_getTabs((tabs) => {
    for (const [tabId, tab] of Object.entries(tabs)) {
        console.log(`tab ${tabId}`, tab);
    }
});
const tabs = await GM.getTabs();

GM_setValue(key, value)

The GM_setValue allows a userscript to set the value of a specific key in the userscript's storage.

The GM_setValue function takes two parameters:

    A string specifying the key for which the value should be set.
    The value to be set for the key. Values (including nested object properties) can be null or of type "object", "string", "number", "undefined" or "boolean".

The GM_setValue function does not return any value. Instead, it sets the provided value for the specified key in the userscript's storage.

Here is an example of how GM_setValue and its async pendant GM.setValue might be used in a userscript:

GM_setValue("someKey", "someData");
await GM.setValue("otherKey", "otherData");

GM_getValue(key, defaultValue)

The GM_getValue function allows a userscript to retrieve the value of a specific key in the extension's storage. It takes two parameters:

    A string specifying the key for which the value should be retrieved.
    A default value to be returned if the key does not exist in the extension's storage. This default value can be of any type (string, number, object, etc.).

The GM_getValue function returns the value of the specified key from the extension's storage, or the default value if the key does not exist.

Here is an example of how the GM_getValue function might be used in a userscript:

const someKey = GM_getValue("someKey", null);
const otherKey = await GM.getValue("otherKey", null);

In this example, the GM_getValue function is called with the key "someKey" and a default value of null. If the "someKey" key exists in the extension's storage, its value will be returned and stored in the someKey variable. If the key does not exist, the default value of null will be returned and stored in the savedTab variable.
GM_deleteValue(key)

Deletes "key" from the userscript's storage.

GM_deleteValue("someKey");
await GM.deleteValue("otherKey");

GM_listValues()

The GM_listValues function returns a list of keys of all stored data.

const keys = GM_listValues();
const asyncKeys = await GM.listValues();

GM_addValueChangeListener(key, (key, old_value, new_value, remote) => void)

The GM_addValueChangeListener function allows a userscript to add a listener for changes to the value of a specific key in the userscript's storage.

The function takes two parameters:

    A string specifying the key for which changes should be monitored.
    A callback function that will be called when the value of the key changes. The callback function should have the following signature:

      function(key, oldValue, newValue, remote) {
          // key is the key whose value has changed
          // oldValue is the previous value of the key
          // newValue is the new value of the key
          // remote is a boolean indicating whether the change originated from a different userscript instance
      }

The GM_addValueChangeListener function returns a "listenerId" value that can be used to remove the listener later using the GM_removeValueChangeListener function. The very same applies to GM.addValueChangeListener and GM.removeValueChangeListener with the only difference that both return a promise;

Here is an example of how the GM_addValueChangeListener function might be used in a userscript:

// Add a listener for changes to the "savedTab" key
var listenerId = GM_addValueChangeListener("savedTab", function(key, oldValue, newValue, remote) {
  // Print a message to the console when the value of the "savedTab" key changes
  console.log("The value of the '" + key + "' key has changed from '" + oldValue + "' to '" + newValue + "'");
});

GM_addValueChangeListener can be used by userscripts to communicate with other userscript instances at other tabs.
GM_removeValueChangeListener(listenerId)

GM_removeValueChangeListener and GM.removeValueChangeListener both get one argument called "listenerId" and remove the change listener with this ID.
GM_xmlhttpRequest(details)

The GM_xmlhttpRequest allows a userscripts to send an HTTP request and handle the response. The function takes a single parameter: an object containing the details of the request to be sent and the callback functions to be called when the response is received.

The object can have the following properties:

    method - string, one of GET, HEAD, POST
    url - string|URL, the destination URL
    headers e.g. user-agent, referer, ... (some special headers are not supported by Safari and Android browsers)
    data - string|Blob|File|Object|Array|FormData|URLSearchParams?, some data to send via a POST request
    redirect one of follow, error or manual; controls what to happen when a redirect is detected (build 6180+, enforces fetch mode)
    cookie a cookie to be patched into the sent cookie set
    binary send the data string in binary mode
    nocache don't cache the resource
    revalidate revalidate maybe cached content
    timeout a timeout in ms
    context a property which will be added to the response object
    responseType one of arraybuffer, blob, json or stream
    overrideMimeType a MIME type for the request
    anonymous don't send cookies with the request (enforces fetch mode)
    fetch use a fetch instead of a XMLHttpRequest request (at Chrome this causes details.timeout and xhr.onprogress to not work and makes xhr.onreadystatechange receive only readyState DONE (==4) events)
    user a user name for authentication
    password a password
    onabort callback to be executed if the request was aborted
    onerror callback to be executed if the request ended up with an error
    onloadstart callback to be executed on load start, provides access to the stream object if responseType is set to stream
    onprogress callback to be executed if the request made some progress
    onreadystatechange callback to be executed if the request's readyState changed
    ontimeout callback to be executed if the request failed due to a timeout
    onload callback to be executed if the request was loaded.

      function(response) {
        // response is an object containing the details of the response
      }

    response has the following attributes:
        finalUrl - the final URL after all redirects from where the data was loaded
        readyState - the request's readyState
        status - the request's status
        statusText - the request's status text
        responseHeaders - the request's response headers
        response - the response data as object if details.responseType was set
        responseXML - the response data as XML document
        responseText - the response data as plain string

GM_xmlhttpRequest returns an object with the following property:

    abort - function to be called to cancel this request

GM.xmlHttpRequest returns a promise that resolves to the response and also has an abort function.

Here is an example of how the GM_xmlhttpRequest function might be used in a userscript:

GM_xmlhttpRequest({
  method: "GET",
  url: "https://example.com/",
  headers: {
    "Content-Type": "application/json"
  },
  onload: function(response) {
    console.log(response.responseText);
  }
});

const r = await GM.xmlHttpRequest({ url: "https://example.com/" }).catch(e => console.error(e));
console.log(r.responseText);

Note: the synchronous flag at details is not supported

Important: if you want to use this method then please also check the documentation about @connect.
GM_webRequest(rules, listener)

Note: this API is experimental and might change at any time. It might also disappear or change during manifest v3 migration.

GM_webRequest (re-)registers rules for web request manipulations and the listener of triggered rules. If you need to just register rules it's better to use @webRequest header. Note, webRequest proceeds only requests with types sub_frame, script, xhr and websocket.
Parameters:

    rules - object[], array of rules with following properties:
        selector - string|object, for which URLs the rule should be triggered, string value is shortening for { include: [selector] }, object properties:
            include - string|string[], URLs, patterns, and regexpes for rule triggering;
            match - string|string[], URLs and patterns for rule trigering;
            exclude - string|string[], URLs, patterns, and regexpes for not triggering the rule;
        action - string|object, what to do with the request, string value "cancel" is shortening for { cancel: true }, object properties:
            cancel - boolean, whether to cancel the request;
            redirect - string|object, redirect to some URL which must be included in any @match or @include header. When a string, redirects to the static URL. If object:
                from - string, a regexp to extract some parts of the URL, e.g. "([^:]+)://match.me/(.*)";
                to - string, pattern for substitution, e.g. "$1://redirected.to/$2";
    listener - function, is called when the rule is triggered, cannot impact on the rule action, arguments:
        info - string, type of action: "cancel", "redirect";
        message - string, "ok" or "error";
        details - object, info about the request and rule:
            rule - object, the triggered rule;
            url - string, URL of the request;
            redirect_url - string, where the request was redirected;
            description - string, error description.

Example

GM_webRequest([
    { selector: '*cancel.me/*', action: 'cancel' },
    { selector: { include: '*', exclude: 'http://exclude.me/*' }, action: { redirect: 'http://new_static.url' } },
    { selector: { match: '*://match.me/*' }, action: { redirect: { from: '([^:]+)://match.me/(.*)',  to: '$1://redirected.to/$2' } } }
], function(info, message, details) {
    console.log(info, message, details);
});

GM_cookie.list(details[, callback])

Note: the GM_cookie API is experimental and might return a not supported error at some Tampermonkey versions.

Tampermonkey checks if the script has @include or @match access to given details.url arguments!
Parameters:

    details object, containing properties of the cookies to retrieve
        url string?, representing the URL to retrieve cookies from (defaults to current document URL)
        domain string?, representing the domain of the cookies to retrieve
        name string?, representing the name of the cookies to retrieve
        path string?, representing the path of the cookies to retrieve
    callback function?, to be called when the cookies have been retrieved. The function will be passed two arguments:
        cookies object[], representing the retrieved cookies
        error string, representing an error message if an error occurred, null otherwise.

The cookie objects have the following properties:

    domain string, representing the domain of the cookie
    firstPartyDomain string?: the first party domain of the cookie.
    hostOnly boolean, indicating whether the cookie is a host-only cookie
    httpOnly boolean, indicating whether the cookie is an HTTP-only cookie
    name string, representing the name of the cookie
    path string, representing the path of the cookie
    sameSite string, indicating the SameSite attribute of the cookie
    secure boolean, indicating whether the cookie requires a secure connection
    session boolean, indicating whether the cookie is a session cookie
    value string, representing the value of the cookie

Example usage:

// Retrieve all cookies with name "mycookie"
GM_cookie.list({ name: "mycookie" }, function(cookies, error) {
  if (!error) {
    console.log(cookies);
  } else {
    console.error(error);
  }
});

// Retrieve all cookies for the current domain
const cookies = await GM.cookies.list()
console.log(cookies);

GM_cookie.set(details[, callback])

Sets a cookie with the given details. Supported properties are defined here.
Parameters:

    details: An object containing the details of the cookie to be set. The object can have the following properties:
        url string?, the URL to associate the cookie with. If not specified, the cookie is associated with the current document's URL.
        name string, the name of the cookie.
        value string, the value of the cookie.
        domain string?, the domain of the cookie.
        firstPartyDomain string?: the first party domain of the cookie.
        path string?, the path of the cookie.
        secure boolean?, whether the cookie should only be sent over HTTPS.
        httpOnly boolean?, whether the cookie should be marked as HttpOnly.
        expirationDate number?, the expiration date of the cookie in seconds since the Unix epoch. If not specified, the cookie never expires.
    callback function?, a function to be called when the operation is complete. The function is passed one argument:
        error string?, if there was an error setting the cookie, this contains an error message. Otherwise, it is undefined.

Example:

GM_cookie.set({
  url: 'https://example.com',
  name: 'name',
  value: 'value',
  domain: '.example.com',
  path: '/',
  secure: true,
  httpOnly: true,
  expirationDate: Math.floor(Date.now() / 1000) + (60 * 60 * 24 * 30) // Expires in 30 days
}, function(error) {
  if (error) {
    console.error(error);
  } else {
    console.log('Cookie set successfully.');
  }
});

GM.cookie.set({
  name: 'name',
  value: 'value'
})
.then(() => {
  console.log('Cookie set successfully.');
})
.catch((error) => {
  console.error(error);
});

GM_cookie.delete(details, callback)

Deletes a cookie.
Parameters:

The details object must contain at least one of the following properties:

    url string?, the URL associated with the cookie. If url is not specified, the current document's URL will be used.
    name string?, the name of the cookie to delete.
    firstPartyDomain string?: the first party domain of the cookie to delete.

The callback function is optional and will be called when the cookie has been deleted or an error has occurred. It takes one argument:

    error string?, an error message, or undefined if the cookie was deleted successfully.

Example:

GM_cookie.delete({ name: 'cookie_name' }, function(error) {
    if (error) {
        console.error(error);
    } else {
        console.log('Cookie deleted successfully');
    }
});

window.onurlchange

If a script runs on a single-page application, then it can use window.onurlchange to listen for URL changes:

// ==UserScript==
...
// @grant window.onurlchange
// ==/UserScript==

if (window.onurlchange === null) {
    // feature is supported
    window.addEventListener('urlchange', (info) => ...);
}

window.close

Usually JavaScript is not allowed to close tabs via window.close. Userscripts, however, can do this if the permission is requested via @grant.

Note: for security reasons it is not allowed to close the last tab of a window.

// ==UserScript==
...
// @grant window.close
// ==/UserScript==

if (condition) {
    window.close();
}

window.focus

window.focus brings the window to the front, while unsafeWindow.focus may fail due to user settings.

// ==UserScript==
...
// @grant window.focus
// ==/UserScript==

if (condition) {
    window.focus();
}

<><![CDATA[...]]></>

CDATA-based way of storing meta data is supported via compatibility option. Tampermonkey tries to automatically detect whether a script needs this option to be enabled.

var inline_src = (<><![CDATA[
    console.log('Hello World!');
]]></>).toString();

eval(inline_src);

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