Introduction to Bookmarklets: JavaScript Everywhere
Tags: bookmarklet, javascript, beginners, quicktips
Published: 2023-09-13 09:50:36

Bookmarklets are an underrated yet powerful tool for web browsing. In this article, we will go through what a bookmarklet is, why you might want to use one instead of plain old JavaScript, and how to create, use, and debug bookmarklets.

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## What is a Bookmarklet?

A bookmarklet is essentially a bookmark in your web browser that runs JavaScript code on the current page when clicked. Instead of taking you to a new webpage, it performs a function on the page you are already on. For example, it can highlight text, execute an API, or even change the web page's entire layout!

Bookmarklets are incredibly convenient for automating tasks or modifying websites to your liking.

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## Why Use Bookmarklet Instead of Vanilla JavaScript?

You might ask, "Why should I use a bookmarklet when I can open the console and run JavaScript code directly?" Here's why:

* **Ease of Use**: Bookmarklets are incredibly easy to use. Once set up, you simply click the bookmark to execute the code. This allows non-technical users to use them as well.
* **Portability**: You can easily share bookmarklets with others. Bookmarklets can also be synced across different devices.

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## How to Create a Bookmarklet?

Creating a bookmarklet is relatively straightforward. Below are the steps:

1. **Write JavaScript Code**: Create a piece of JavaScript code you want to run. Make sure it's a standalone piece of code that doesn't rely on any external libraries.

2. **Create Bookmark Manually**: Add a new bookmark to your browser via the bookmark manager. Give it a name and save it.

    | Browser                                                                                    | Bookmark Manager Shortcut |
    | ------------------------------------------------------------------------------------------ | ------------------------- |
    | [Chrome](https://support.google.com/chrome/answer/188842)                                  | `chrome://bookmarks`      |
    | [Safari](https://support.apple.com/guide/safari/bookmark-webpages-to-revisit-ibrw1039/mac) | `bookmarks://`            |
    | [FireFox](https://support.mozilla.org/en-US/kb/bookmarks-firefox)                          | `Command + Shift + O`     |

3. **Add Code**: Edit the bookmark and place `javascript:` before your code in the URL field.

    **Example**:

    ```javascript
    javascript:alert('Hello, World!');
    ```

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## How to Use a Bookmarklet?

Using a bookmarklet is as simple as clicking it. Here's how:

1. **Navigate to the Page**: Go to the webpage where you want to run your bookmarklet.

2. **Click the Bookmarklet**: Simply click the bookmarklet in your bookmarks bar.

The JavaScript code will execute and perform its function on the current webpage.

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## How to Debug a Bookmarklet?

If your bookmarklet isn't working as expected, debugging can help identify the problem.

1. **Console Errors**: Open your browser's developer console to look for errors. `console.log()` statements work in bookmarklets!
1. **Alerts**: Use `alert()` statements within the bookmarklet code to check if parts of it are running as they should.
1. **No Comments**: Remove all comments from your code. Comments break bookmarklets.
1. **Code Review**: Double-check your code for syntax errors or logical issues.

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And there you have it! Bookmarklets are an exciting way to extend your browser's functionality and automate web tasks.

Good luck coding!