@react-input2/mask

@react-input/mask

✨ Apply any mask to the input using a provided component or a hook bound to the input element.

Installation

npm i @react-input2/mask

or using yarn:

yarn add @react-input2/mask

Unique properties

Name	Type	Default	Description
component	Component		Not used in the useMask hook. Serves to enable the use of custom components, for example, if you want to use your own styled component with the ability to mask the value (see «Integration with custom components»).
mask	string	""	Input mask, replacement is used to replace characters.
replacement	string | object	{}	Sets the characters replaced in the mask, where "key" is the replaced character, "value" is the regular expression to which the input character must match (see «Replacement»). It is possible to pass the replacement character as a string, then replacement="_" will default to replacement={{ _: /./ }}. Keys are ignored as you type.
showMask	boolean	false	Controls the display of the mask, for example, +7 (912) ___-__-__ instead of +7 (912.
separate	boolean	false	Stores the position of the entered characters. By default, input characters are non-breaking, which means that if you remove characters in the middle of the value, the characters are shifted to the left, forming a non-breaking value, which is the behavior of input. For example, with true, the possible value is +7 (912) ___-67-__, with false - +7 (912) 67_-__-__.
modify	function		Function triggered before masking. Allows you conditionally change the properties of the component that affect masking. Valid values ​​for modification are mask, replacement, showMask and separate. This is useful when you need conditionally tweak the displayed value to improve UX (see «Modify»).
onMask	function		Handler for the custom event input-mask. Called asynchronously after the change event, accessing the detail property containing additional useful information about the value. (see «Mask event»).

You can also pass other properties available element input default or your own components, when integrated across the property component.

Usage

The @react-input/mask package provides two options for using a mask. The first is the InputMask component, which is a standard input element with additional logic to handle the input. The second is using the useMask hook, which needs to be linked to the input element through the ref property.

One of the key features of the @react-input/mask package is that it only relies on user-supplied characters, so you can safely include any character in the mask without fear of the «unexpected behavior».

Let's see how you can easily implement a mask for entering a phone number using the InputMask component:

import { InputMask } from '@react-input/mask';

export default function App() {
  return <InputMask mask="+7 (___) ___-__-__" replacement={{ _: /\d/ }} />;
}

You can work with the InputMask component in the same way as with the input element, with the difference that the InputMask component uses additional logic to process the value.

Now the same thing, but using the useMask hook:

import { useMask } from '@react-input/mask';

export default function App() {
  const inputRef = useMask({ mask: '+7 (___) ___-__-__', replacement: { _: /\d/ } });

  return <input ref={inputRef} />;
}

The useMask hook takes the same properties as the InputMask component, except for the component properties. Both approaches are equivalent, but the use of the InputMask component provides additional capabilities, which will be discussed in the section «Integration with custom components».

The InputMask component does not change the value passed in the value or defaultValue property of the input element, so specify as the initialized value one that can match the masked value at any stage of input. If you make a mistake, you will see a warning about it in the console.

Replacement

The replacement property sets the characters to be replaced in the mask, where "key" is the replaced character, "value" is the regular expression to which the input character must match. You can set one or more replaceable characters with different regexps,

like this:

import { InputMask } from '@react-input/mask';

export default function App() {
  return <InputMask mask="dd.mm.yyyy" replacement={{ d: /\d/, m: /\d/, y: /\d/ }} showMask separate />;
}

It is possible to pass the replacement character as a string, then any characters will be allowed. For example, replacement="_" is the same as replacement={{ _: /./ }}.

Do not use entered characters as replacement keys. For example, if you only allow numbers to be entered, given that the user can enter "9", then you should not set replacement to { 9: /\d/ }, because keys are ignored when typing. Thus, the input of any numbers except "9" will be allowed.

Modify

The modify function is triggered before masking and allows you conditionally change the properties of the component that affect the masking.

The modify function expects to return an object containing the data to modify, optionally including mask, replacement, showMask and separate, or to return undefined. Changes will be only applied to those properties that were returned, so you can change any property as you like, or not change any property by passing undefined.

The modify function takes a value without mask characters that is valid at the time of input. For example, if the mask property has the value +7 (___) ___-__-__ and the previous value is +7 (123) ___-__-__ and the user entered the character "4" at the ninth index of the value, then modify will take the value "1234". Note that there are no mask characters including "7" as well. Using this value you can modify the properties with the expected result.

Let's consider a possible situation when we need to change the mask depending on the phone city code:

import { InputMask } from '@react-input/mask';

export default function App() {
  const modify = (input: string) => {
    return { mask: input[0] === '7' ? '+_ (___) ___-__-__' : undefined };
  };

  return <InputMask mask="+_ __________" replacement={{ _: /\d/ }} modify={modify} />;
}

The advantage of this approach is that you do not need to store the state of the component to change its properties, the modification happens in the already running masking process.

Mask event

It can be useful to have additional data about the value at hand, for this you can use the input-mask event.

The input-mask event is fired asynchronously after the change event, in addition, the input-mask event object has a detail property that contains additional useful information about the value:

Name	Type	Description
value	string	Masked value (same as event.target.value).
input	string	Value without mask characters.
parts	object[]	Parts of the masked value, where each object contains the character type: replacement - the replacement character; mask - mask character; input is the character entered by the user.
pattern	string	A regular expression of type string that the masked value must match.
isValid	boolean	true if the mask is full and matches the pattern value.

By itself, the input-mask event can completely replace the change event, but you should not use it if it is not necessary, since the input-mask event is called asynchronously after the change event has completed, which may lead to additional rendering of the component. Consider the input-mask event as an optional feature, not a required feature.

You can use both the input-mask event and the change event to save the state, however, if you don't need additional parameters in the detail property, prefer the change event.

An example of using the input-mask event:

import { useState } from 'react';

import { InputMask, type MaskEventDetail } from '@react-input/mask';

export default function App() {
  const [detail, setDetail] = useState<MaskEventDetail | null>(null);

  return (
    <>
      <InputMask
        mask="1yyy"
        replacement={{ _: /\d/ }}
        value={detail?.value ?? ''}
        onMask={(event) => setDetail(event.detail)}
      />
      {detail?.input && !detail.isValid && <span>The field is not filled.</span>}
    </>
  );
}

Note that in the example above we are checking for detail.input, this is because we only want to display the error text if the user entered numbers. Thus, if you only want the numbers from the masked value, the event.detail.input property will not contain the numbers from the mask, since they are mask characters. So, in the example above (mask="1yyy"), if you enter the value "991", the value in the property event.detail.input will match the entered value "991", but not "1991".

Integration with custom components

The InputMask component makes it easy to integrate with custom components allowing you to use your own styled components. To do this, you need to pass the custom component to the forwardRef method provided by React. forwardRef allows you automatically pass a ref value to a child element (more on forwardRef).

Then place your own component in the component property. The value for the component property can be either function components or class components.

With this approach, the InputMask component acts as a HOC, adding additional logic to the input element.

Here's how to do it:

import { forwardRef } from 'react';

import { InputMask } from '@react-input/mask';

interface CustomInputProps {
  label: string;
}

// Custom input component
const CustomInput = forwardRef<HTMLInputElement, CustomInputProps>(({ label }, forwardedRef) => {
  return (
    <>
      <label htmlFor="custom-input">{label}</label>
      <input ref={forwardedRef} id="custom-input" />
    </>
  );
});

// Component with InputMask
export default function App() {
  return <InputMask component={CustomInput} mask="___-___" replacement="_" label="Label for custom component" />;
}

The InputMask component will not forward properties available only to the InputMask, so as not to break the logic of your own component.

Integration with Material UI

If you are using Material UI, you need to create a component that returns a InputMask and pass it as a value to the inputComponent property of the Material UI component.

In this case, the Material UI component will pass an additional inputRef property to your component, which you will need to pass as the value for the ref property of the element of the InputMask component.

Here's how to do it using the InputMask component:

import { forwardRef } from 'react';

import { InputMask, type InputMaskProps } from '@react-input/mask';
import { TextField } from '@mui/material';

// Component with InputMask
const ForwardedInputMask = forwardRef<HTMLInputElement, InputMaskProps>((props, forwardedRef) => {
  return <InputMask ref={forwardedRef} mask="___-___" replacement="_" {...props} />;
});

// Component with Material UI
export default function App() {
  return (
    <TextField
      InputProps={{
        inputComponent: ForwardedInputMask,
      }}
    />
  );
}

or using the useMask hook:

import { useMask } from '@react-input/mask';
import { TextField } from '@mui/material';

export default function App() {
  const inputRef = useMask({ mask: '___-___', replacement: '_' });

  return <TextField inputRef={inputRef} />;
}

Usage with TypeScript

The @react-input/mask package is written in TypeScript, so you have full type support out of the box. In addition, you can import the types you need for your use:

import { useState } from 'react';

import { InputMask, type MaskEventDetail, type MaskEventHandler, type Modify } from '@react-input/mask';

export default function App() {
  const [detail, setDetail] = useState<MaskEventDetail | null>(null);

  // Or `event: MaskEvent`
  const handleMask: MaskEventHandler = (event) => {
    setDetail(event.detail);
  };

  const modify: Modify = (input) => {
    return undefined;
  };

  return <InputMask mask="___-___" replacement="_" modify={modify} onMask={handleMask} />;
}

Property type support

Since the InputMask component supports two use cases (as an input element and as an HOC for your own component), InputMask takes both use cases into account to support property types.

By default, the InputMask component is an input element and supports all the attributes supported by the input element. But if the component property was passed, the InputMask will additionally support the properties available to the integrated component. This approach allows you to integrate your own component as conveniently as possible, not forcing you to rewrite its logic, but using a mask where necessary.

import { InputMask } from '@react-input/mask';

export default function App() {
  // Here, since no `component` property was passed,
  // `InputMask` returns an `input` element and takes the type:
  // `InputMaskProps & React.InputHTMLAttributes<HTMLInputElement>`
  return <InputMask mask="___-___" replacement="_" />;
}

import { InputMask } from '@react-input/mask';

import { CustomInput, type CustomInputProps } from './CustomInput';

export default function App() {
  // Here, since the `component` property was passed,
  // `InputMask` returns the integrated component and takes the type:
  // `InputMaskProps & CustomInputProps` (the same as `InputMaskProps<CustomInputProps>`)
  return <InputMask component={CustomInput} mask="___-___" replacement="_" />;
}

You may run into a situation where you need to pass rest parameters (...rest) to the InputMask component. If the rest parameters is of type any, the component property will not be typed correctly, as well as the properties of the component being integrated. this is typical TypeScript behavior for dynamic type inference.

To remedy this situation and help the InputMask type correctly the properties of your component, you can pass the property type of your component directly to the InputMask component.

import { InputMask } from '@react-input/mask';

import { CustomInput, type CustomInputProps } from './CustomInput';

export default function Component(props: any) {
  return <InputMask<CustomInputProps> component={CustomInput} mask="___-___" replacement="_" {...props} />;
}

Testing

Because each input performs the necessary calculations to set the formatting of the value, you need to set a delay between character inputs when testing the input in your application, otherwise the test may not succeed due to the necessary changes between inputs not taking effect.

The recommended delay time is 15 milliseconds, however, you may need to set a different time, which can be found experimentally.

Other packages from @react-input

• @react-input2/number-format - apply locale-specific number, currency, and percentage formatting to input using a provided component or hook bound to the input element.

Feedback

If you find a bug or want to make a suggestion for improving the package, open the issues on GitHub or email [e-mail].

Support the project with a star ⭐ on GitHub.

License

MIT © Nikolay Goncharuk