npm package: @marolla/react-input-mask
Description: Masked input component for React 18
Author: Paulo Marolla
Latest version: 1.0.2

# @marolla/react-input-mask
**@marolla/react-input-mask** is the stable version of the react-input-mask library for React 18 or later.

If you need support for older versions, use [version 2](https://www.npmjs.com/package/react-input-mask).

####  [Demo](http://sanniassin.github.io/react-input-mask/demo.html)

# Table of Contents

*  [Installation](#installation)

*  [Usage](#usage)

*  [Properties](#properties)

*  [Known Issues](#known-issues)

  

# Installation

**npm**

```npm install @marolla/react-input-mask --save```

**yarn**

```yarn add @marolla/react-input-mask```
  

# Usage

```jsx

import React from  "react"

import InputMask from  "@marolla/react-input-mask";

  

function  DateInput(props)  {

return  <InputMask  mask="99/99/9999"  onChange={props.onChange}  value={props.value}  />;

}

```

  

# Properties

| Name | Type | Default | Description |

| :-----------------------------------------: | :-------------------------: | :-----: | :--------------------------------------------------------------------- |

| **[`mask`](#mask)** | `{String\|Array<String, RegExp>}` | | Mask format |

| **[`maskPlaceholder`](#maskplaceholder)** | `{String}` | `_` | Placeholder to cover unfilled parts of the mask |

| **[`alwaysShowMask`](#alwaysshowmask)** | `{Boolean}` | `false` | Whether mask prefix and placeholder should be displayed when input is empty and has no focus |

| **[`beforeMaskedStateChange`](#beforemaskedstatechange)** | `{Function}` | | Function to modify value and selection before applying mask |

| **[`children`](#children)** | `{ReactElement}` | | Custom render function for integration with other input components |

  
  

###  `mask`

  

Mask format. Can be either a string or array of characters and regular expressions.<br  /><br  />

  
  

```jsx

<InputMask  mask="99/99/99"  />

```

Simple masks can be defined as strings. The following characters will define mask format:

  

| Character | Allowed input |

| :-------: | :-----------: |

| 9 | 0-9 |

| a | a-z, A-Z |

| * | 0-9, a-z, A-Z |

  

Any format character can be escaped with a backslash.<br  /><br  />

  
  

More complex masks can be defined as an array of regular expressions and constant characters.

```jsx

// Canadian postal code mask

const firstLetter =  /(?!.*[DFIOQU])[A-VXY]/i;

const letter =  /(?!.*[DFIOQU])[A-Z]/i;

const digit =  /[0-9]/;

const mask =  [firstLetter, digit, letter,  " ", digit, letter, digit];

return  <InputMask  mask={mask}  />;

```

  
  

###  `maskPlaceholder`

```jsx

// Will be rendered as 12/--/--

<InputMask  mask="99/99/99"  maskPlaceholder="-"  value="12"  />

  

// Will be rendered as 12/mm/yy

<InputMask  mask="99/99/99"  maskPlaceholder="dd/mm/yy"  value="12"  />

  

// Will be rendered as 12/

<InputMask  mask="99/99/99"  maskPlaceholder={null}  value="12"  />

```

Character or string to cover unfilled parts of the mask. Default character is "\_". If set to `null` or empty string, unfilled parts will be empty as in a regular input.

  
  

###  `alwaysShowMask`

  

If enabled, mask prefix and placeholder will be displayed even when input is empty and has no focus.

  
  

###  `beforeMaskedStateChange`

In case you need to customize masking behavior, you can provide `beforeMaskedStateChange` function to change masked value and cursor position before it's applied to the input.

  

It receieves an object with `previousState`, `currentState` and `nextState` properties. Each state is an object with `value` and `selection` properites where `value` is a string and selection is an object containing `start` and `end` positions of the selection.

1.  **previousState:** Input state before change. Only defined on `change` event.

2.  **currentState:** Current raw input state. Not defined during component render.

3.  **nextState:** Input state with applied mask. Contains `value` and `selection` fields.

  

Selection positions will be `null` if input isn't focused and during rendering.

  

`beforeMaskedStateChange` must return a new state with `value` and `selection`.

  

```jsx

// Trim trailing slashes

function  beforeMaskedStateChange({  nextState  })  {

let  { value }  = nextState;

if  (value.endsWith("/"))  {

value = value.slice(0,  -1);

}

  

return  {

...nextState,

value

};

}

  

return  <InputMask  mask="99/99/99"  maskPlaceholder={null}  beforeMaskedStateChange={beforeMaskedStateChange}  />;

```

  

Please note that `beforeMaskedStateChange` executes more often than `onChange` and must be pure.

  
  

###  `children`

To use another component instead of regular `<input />` provide it as children. The following properties, if used, should always be defined on the `InputMask` component itself: `onChange`, `onMouseDown`, `onFocus`, `onBlur`, `value`, `disabled`, `readOnly`.

```jsx

import React from  'react';

import InputMask from  '@marolla/react-input-mask';

import MaterialInput from  '@material-ui/core/Input';

  

// Will work fine

function  Input(props)  {

return  (

<InputMask  mask="99/99/9999"  value={props.value}  onChange={props.onChange}>

<MaterialInput  type="tel"  disableUnderline  />

</InputMask>

);

}

  

// Will throw an error because InputMask's and children's onChange props aren't the same

function  InvalidInput(props)  {

return  (

<InputMask  mask="99/99/9999"  value={props.value}>

<MaterialInput  type="tel"  disableUnderline  onChange={props.onChange}  />

</InputMask>

);

}

```

  

# Known Issues

### Autofill

Browser's autofill requires either empty value in input or value which exactly matches beginning of the autofilled value. I.e. autofilled value "+1 (555) 123-4567" will work with "+1" or "+1 (5", but won't work with "+1 (\_\_\_) \_\_\_-\_\_\_\_" or "1 (555)". There are several possible solutions:

1. Set `maskChar` to null and trim space after "+1" with `beforeMaskedStateChange` if no more digits are entered.

2. Apply mask only if value is not empty. In general, this is the most reliable solution because we can't be sure about formatting in autofilled value.

3. Use less formatting in the mask.

  

Please note that it might lead to worse user experience (should I enter +1 if input is empty?). You should choose what's more important to your users — smooth typing experience or autofill. Phone and ZIP code inputs are very likely to be autofilled and it's a good idea to care about it, while security confirmation code in two-factor authorization shouldn't care about autofill at all.

  

### Cypress tests

The following sequence could fail

```js

cy.get("input")

.focus()

.type("12345")

.should("have.value",  "12/34/5___");  // expected <input> to have value 12/34/5___, but the value was 23/45/____

````

  

Since [focus is not an action command](https://docs.cypress.io/api/commands/focus.html#Focus-is-not-an-action-command), it behaves differently than the real user interaction and, therefore, less reliable.

  

There is a few possible workarounds

```js

// Start typing without calling focus() explicitly.

// type() is an action command and focuses input anyway

cy.get("input")

.type("12345")

.should("have.value", "12/34/5___");

  

// Use click() instead of focus()

cy.get("input")

.click()

.type("12345")

.should("have.value", "12/34/5___");

  

// Or wait a little after focus()

cy.get("input")

.focus()

.wait(50)

.type("12345")

.should("have.value", "12/34/5___");

````

 ### Author 🤝
  **@marolla/react-input-mask** uses **react-input-mask** and **react-input-mask-next** as a base. Both libraries are having bugs in the React 18 version, so I cloned the project and fixed the bugs and created **@marolla/react-input-mask**.