GRUZF MaskInput

Input masking component for React. Made with attention to UX.

GRUZF MaskInput is written in TypeScript.

Table of Contents

• Install
• Usage
• Properties
  • mask
  • maskPlaceholder
  • alwaysShowMask
  • beforeMaskedStateChange
  • unmask
  • fullFilled
  • onlyDigitAndLetter
• maskedString
• Known Issues

Install

npm install @gruzf/mask-input

or

yarn add @gruzf/mask-input

⚠️ @gruzf/mask-input requires React 16.8.0 or later.

Usage

import MaskInput from "@gruzf/mask-input";
import React from "react";

function DateInput(props) {
  return (
    <MaskInput
      mask="99/99/9999"
      onChange={props.onChange}
      value={props.value}
    />
  );
}

Properties

Name	Type	Default	Description
mask	{String|Array<String, RegExp>}	"[phone]"	Mask format
maskPlaceholder	{String|null}	null	Placeholder to cover unfilled parts of the mask
alwaysShowMask	{Boolean}	false	Whether mask prefix and placeholder should be displayed when input is empty and has no focus
beforeMaskedStateChange	{Function}		Function to modify value and selection before applying mask
unmask	{Boolean}	false	Value format
fullFilled	{Boolean}	type==="tel"	Value will be empty string until the user completely fills in the masked field.
onlyDigitAndLetter	{Boolean}	type==="tel"	Value will contain only letters and digits
children	{ReactElement}		Custom render function for integration with other input components

And other InputHTMLAttributes that are passed to the <input/> or to the passed children wich contains <input/>.

mask

Mask format. Can be either a string or array of characters and regular expressions. Default mask: "[phone]". If the mask was not passed, the default input type attribute will switch to 'tel'

<MaskInput mask="99/99/99" />

The same mask by regex array:

<MaskInput mask={[/\d/, /\d/, "\\", /\d/, /\d/, "\\", /\d/, /\d/]} />

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.

More complex masks can be defined as an array of regular expressions and constant characters.

// 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 <MaskInput mask={mask} />;

maskPlaceholder

Default: null

Character or string to cover unfilled parts of the mask.

// Will be rendered as 12/--/--
<MaskInput mask="99/99/99" maskPlaceholder="-" value="12" />

// Will be rendered as 12/mm/yy
<MaskInput mask="99/99/99" maskPlaceholder="dd/mm/yy" value="12" />

// Will be rendered as 12/
<MaskInput mask="99/99/99" maskPlaceholder={null} value="12" />

alwaysShowMask

Default: false

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.

// Trim trailing slashes
function beforeMaskedStateChange({ nextState }) {
  let { value } = nextState;
  if (value.endsWith("/")) {
    value = value.slice(0, -1);
  }

  return {
    ...nextState,
    value
  };
}

return <MaskInput mask="99/99/99" beforeMaskedStateChange={beforeMaskedStateChange} />;

import MaskInput, { BeforeMaskedStateChangeStates } from "@gruzf/mask-input";

let mask = [/[0-2]/, /\d/, ":", /[0-5]/, /\d/];

// Timer input like "12:59"
const beforeMaskedStateChange = (states: BeforeMaskedStateChangeStates) => {
  let { value, selection } = states.nextState;

  if (value.startsWith("2")) {
    mask[1] = /[0-3]/;
  } // To block 24, 25, etc.
  else {
    mask[1] = /\d/;
  } // To allow 05, 12, etc.
  return { value, selection };
};

return <MaskInput mask={mask} beforeMaskedStateChange={beforeMaskedStateChange} />;

Please note that beforeMaskedStateChange executes more often than onChange and must be pure.

unmask

Default: false

If enabled, displayed value will be with mask, but input value will be without mask.

• false:

    // default mask: "[phone]"
    // passed value: "[phone]"
    // displayed value: "[phone]"
    // input value: "[phone]"
    return <MaskInput value="[phone]"/>

• true:

    // default mask: "[phone]"
    // passed value: "[phone]"
    // displayed value: "[phone]"
    // input value: "1234567890"
    return <MaskInput value="[phone]" unmask/>

fullFilled

Default: prop type === "tel"

If enabled, input value will be empty string until the user completely fills in the masked field.

• false:

    // type !== "tel" => fullFilled={false}
    // displayed value: "1234 567"
    // input value: "1234 567"
    return <MaskInput  mask={"9999 9999 9999 9999"} value="1234567" />

• true:

  • not filled

      // displayed value: "1234 567"
      // input value: ""
      return <MaskInput  mask={"9999 9999 9999 9999"} value="1234567" fullFilled/>

  • full filled

      // displayed value: "1234 5678 9012 3456"
      // input value: "1234 5678 9012 3456"
      return <MaskInput  mask={"9999 9999 9999 9999"} value="1234567890123456" fullFilled/>

onlyDigitAndLetter

Default: prop type === "tel"

If enabled, input value will contain only digits and letters.

  // default mask: "[phone]"
  // passed value: "[phone]"
  // displayed value: "[phone]"
  // onlyDigitAndLetter = true because prop `type` === "tel"
  // input value: "71234567890"
    return <MaskInput value="[phone]"/>

  // passed value: "--74_vg_R"
  // displayed value: "--74_vg_R"
  // input value: ""74vgR""
  return <MaskInput mask="--99_aa_*" value="--74_vg_R" onlyDigitAndLetter/>

children

To use another component instead of regular <input /> provide it as children. The following properties, if used, should always be defined on the MaskInput component itself: onChange, onMouseDown, onFocus, onBlur, value, disabled, readOnly.

import MaskInput from "@gruzf/mask-input";
import { TextField } from "@mui/material";
import React from "react";

// Will work fine
function Input(props) {
  return (
    <MaskInput
      mask="99/99/9999"
      value={props.value}
      onChange={props.onChange}
      type="tel"
    >
      <TextField size="small" variant="filled" />
    </MaskInput>
  );
}

// Will throw an error because MaskInput's and children's onChange props aren't the same
function InvalidInput(props) {
  return (
    <MaskInput mask="99/99/9999" value={props.value}>
      <TextField type="tel" disableUnderline onChange={props.onChange} />
    </MaskInput>
  );
}

maskedString

You can use function maskedString to apply your mask on a string.

maskedString(value, mask, type)

• value - string
• mask - mask to apply on your value
• type - type of your value: "text" or "tel". Default: "tel"

import { maskedString } from "@gruzf/mask-input";

maskedString("1234567890", "[phone]"); // [phone]

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 "[phone]" 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.