npm package: @im-open/text-mask-core
Description: Core of https://github.com/im-open/text-mask
Author: M.K. Safi
Latest version: 5.2.0

# Text Mask Core

This module contains the core functions that power Text Mask. Text Mask
has wrappers for Angular1, Angular2, Ember, React and Vue which can be used directly.

However, Text Mask Core functions could be useful on their own. That's why they are published
and documented here as a separate module.

## Getting started

To download the script, use npm.

```bash
npm i text-mask-core --save
```

### Include it

After installing with npm, you could possibly do something like this from your `index.html`:

```html
<script src="./node_modules/text-mask-core/dist/textMaskCore.js"></script>
```

Including this file in your source code will expose the global object `textMaskCore`.

Or if you're using Node.js or a bundler such as webpack or Browserify, you can require
`textMaskCore` as such:

```js
var textMaskCore = require("text-mask-core");
```

## How to use

`textMaskCore` exposes three functions:

- createTextMaskInputElement
- conformToMask
- adjustCaretPosition

### Overview

The general idea is to take user input, conform it to your desired mask using `conformToMask`,
and then apply the output of `conformToMask` to the value of the HTML input element.
Once you do that however, the caret position will be lost. You can then use `adjustCaretPosition`
to restore the caret to its proper position.

---

## API documentation

### `createTextMaskInputElement(config)`

This function takes a configuration and returns an object with an `update` method. The `update` method is used to conform the raw value to the mask you provide in the config.

```js
// the config requires a `mask` and a reference to an `input` element.
const textMaskConfig = { inputElement, mask };

// initialize text mask
const textMaskInputElement = createTextMaskInputElement(textMaskConfig);

// call `update` to conform the `inputElement.value` to the provided `mask`.
textMaskInputElement.update();
```

The `textMaskConfig` requires a `mask` and a reference to the `inputElement`. See the [documentation here](https://github.com/im-open/text-mask/blob/master/componentDocumentation.md#readme) for more information on the properties that the `textMaskConfig` accepts.

The default use-case is for the `textMaskConfig` to be passed to the `createTextMaskInputElement` method when you initialize Text Mask. However, you can also pass the `value` and `textMaskConfig` to the `update` method.

```js
const textMaskConfig = { inputElement, mask };

// initialize text mask without a config (or with a default config)
const textMaskInputElement = createTextMaskInputElement();

// call `update` with the raw value and config
textMaskInputElement.update(inputElement.value, textMaskConfig);
```

The `update` method should be called every time the `inputElement.value` changes.

---

### `conformToMask(rawValue, mask, config)`

This function takes three arguments:

- rawValue (string): the string value that you want to conform to the mask
- mask (array or function): the mask to which you want the string to conform. You can find
  [mask documentation here](https://github.com/im-open/text-mask/blob/master/componentDocumentation.md#readme).
- config (object): config object. See below for details

This function returns an object with a property `conformedValue` (string).

```js
const results = conformToMask("5554833902", [
  "(",
  /[1-9]/,
  /\d/,
  /\d/,
  ")",
  " ",
  /\d/,
  /\d/,
  /\d/,
  "-",
  /\d/,
  /\d/,
  /\d/,
  /\d/,
]);

results.conformedValue; // '(555) 483-3902'
```

#### config

The `config` object takes the following values

- `guide` (boolean) (defaults to `true`): this tells `conformToMask` whether you want the conformed
  string to contain a guide or no. The `guide` is basically the placeholder character and the
  mask hard characters. For example, with mask `['(', /[1-9]/, /\d/, /\d/, ')', ' ', /\d/, /\d/, /\d/, '-', /\d/, /\d/, /\d/, /\d/]`, input `123` with `guide` set to
  `true` would return `(123) ___-____`. With `guide` set to `false`, it would return `(123) `.

- `previousConformedValue` (string) (required): this is the previous `output` of `conformToMask`.
  If you're calling `conformToMask` for the first time, you don't have to pass this value.

- `placeholderChar` (string) (optional): for documentation on this key, [see this section of the component
  documentation page](https://github.com/im-open/text-mask/blob/master/componentDocumentation.md#placeholderChar).

```js
const results = conformToMask("5554833902", [
  "(",
  /[1-9]/,
  /\d/,
  /\d/,
  ")",
  " ",
  /\d/,
  /\d/,
  /\d/,
  "-",
  /\d/,
  /\d/,
  /\d/,
  /\d/,
]);

results.conformedValue; // '(555) 483-3902'
```

Whenever the value of the `input` element changes, you can pass that value to `conformToMask`
and it'll make sure that the string looks like the given mask. You can then set that conformed
string as the new value of the `input` element.

---

### `adjustCaretPosition(argumentsObject)`

When you set the value of the `input` element, you lose the position of the caret. This function
helps you restore the position.

`adjustCaretPosition` takes the following object of arguments:

- `previousConformedValue` (string): the string value of the `input` before the last time you set
  its value. If you're calling this function for the first time, you can pass an empty string.
- `conformedValue` (string): the `conformedValue` returned from the last call to `conformToMask`
- `currentCaretPosition` (integer): the position of the caret right before you called this
  function
- `rawValue` (string): value of the input element
- `placeholderChar` (string): placeholder character
- `placeholder` (string): the generated placeholder
- `indexesOfPipedChars` (array): an array of piped characters returned from the last call to the `pipe` function
- `caretTrapIndexes` (array): an array of caret trap indexes

`adjustCaretPosition` will return an integer representing the index of where the caret should be
moved to next.