@react-input/number-format

@react-input/number-format

✨ Apply locale-specific number, currency, and percentage formatting to input using a provided component or hook bound to the input element.

Installation

npm i @react-input/number-format

or using yarn:

yarn add @react-input/number-format

Unique properties

Name	Type	Default	Description
component	Component		Not used in the useNumberFormat hook. Serves to enable the use of custom components, for example, if you want to use your own styled component with the ability to format the value (see «Integration with custom components»).
locales	string | string[]		The locale is specified as a string , or an array of such strings in order of preference. By default, the locale set in the environment (browser) is used. For the general form and interpretation of the locales argument, see Locale identification and negotiation.
format	"decimal" | "currency" | "percent" | "unit"	"decimal"	The formatting style to use.
currency	string		The currency to use in currency formatting. Possible values are the ISO 4217 currency codes, such as "USD" for the US dollar, "EUR" for the euro, or "CNY" for the Chinese RMB — see the Current currency & funds code list. If the format is "currency", the currency property must be provided.
currencyDisplay	"symbol" | "narrowSymbol" | "code" | "name"	"symbol"	How to display the currency in currency formatting.
unit	string		The unit to use in unit formatting, Possible values are core unit identifiers, defined in UTS #35, Part 2, Section 6. Pairs of simple units can be concatenated with "-per-" to make a compound unit. If the format is "unit", the unit property must be provided.
unitDisplay	"short" | "long" | "narrow"	"short"	The unit formatting style to use in unit formatting.
signDisplay	"auto" | "never" | "always" | "exceptZero"	"auto"	When to display the sign for the number.
groupDisplay	"auto" | boolean	"auto"	Whether to use grouping separators, such as thousands separators or thousand/lakh/crore separators.
minimumIntegerDigits	number	1	The minimum number of integer digits to use. A value with a smaller number of integer digits than this number will be left-padded with zeros (to the specified length) when formatted.
maximumIntegerDigits	number		The maximum number of integer digits to use.
minimumFractionDigits	number		The minimum number of fraction digits to use. The default for plain number and percent formatting is 0. The default for currency formatting is the number of minor unit digits provided by the ISO 4217 currency code list (2 if the list doesn't provide that information).
maximumFractionDigits	number		The maximum number of fraction digits to use. The default for plain number formatting is the larger of minimumFractionDigits and 3. The default for currency formatting is the larger of minimumFractionDigits and the number of minor unit digits provided by the ISO 4217 currency code list (2 if the list doesn't provide that information). The default for percent formatting is the larger of minimumFractionDigits and 0.
onNumberFormat	function		Handler for the custom event input-number-format. Called asynchronously after the change event, accessing the detail property containing additional useful information about the value. (see «Number format event»).

Since the package is based on the Intl.NumberFormat constructor, it is important to consider that the functionality of both the package itself and its properties will depend on your browser versions. You can view support for browser versions here.

If you are using TypeScript, the properties of the InputNumberFormat component will be typed based on your version of TypeScript, so make sure you are using the latest stable version of TypeScript in your project.

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

Usage

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

One of the key features of the @react-input/number-format package is that it can format numbers according to the desired language using the Intl.NumberFormat constructor.

Let's see how we can easily implement formatting based on the given locale and the minimum number of decimal places using the InputNumberFormat component:

import { InputNumberFormat } from '@react-input/number-format';

export default function App() {
  return <InputNumberFormat locales="en" maximumFractionDigits={2} />;
}

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

Now the same thing, but using the useNumberFormat hook:

import { useNumberFormat } from '@react-input/number-format';

export default function App() {
  const inputRef = useNumberFormat({
    locales: 'en',
    maximumFractionDigits: 2,
  });

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

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

Initializing the value

To support the concept of controlled input, @react-input/number-format does not change the value passed in the value property of the input element, which means that the value in the state exactly matches the value in the input, so set the initialized value to something that can match the formatted value at any point in the input. If you make a mistake, you will see a warning in the console about it.

With controlled input, when the input value is not formatted, you should use the format utility described in the chapter «Utils» to substitute the correct value, for example:

import { useState } from 'react';
import { useNumberFormat, format } from '@react-input/number-format';

const options = { locales: 'en', maximumFractionDigits: 2 };

export default function App() {
  const inputRef = useNumberFormat(options);
  const defaultValue = format(123456789, options);

  const [value, setValue] = useState(defaultValue); // `defaultValue` or '123,456,789'

  return <input ref={inputRef} value={value} onChange={(event) => setValue(event.target.value)} />;
}

With uncontrolled input, you do not need to worry about the input value being unformatted, as the value will be formatted automatically upon initialization.

For consistent and correct behavior, the type property of the input element or the InputNumberFormat component must be set to "text" (the default). If you use other values, the formatting will not be applied and you will see a warning in the console.

Examples of using

The base use without specifying a locale returns a formatted string in the default locale and with default options:

import { InputNumberFormat } from '@react-input/number-format';

export default function App() {
  // Entering 3500 will print '3,500' to the console if in US English locale
  return <InputNumberFormat onChange={(event) => console.log(event.target.value)} />;
}

The following example show some variations of localized number formats. To get the format of the language used in your application's user interface, be sure to specify that language (and possibly some fallback languages) with the locales argument:

import { InputNumberFormat } from '@react-input/number-format';

// Entering 123456.789 will print:

export default function App() {
  return (
    <>
      {/* India uses thousands/lakh/crore separators */}
      <InputNumberFormat
        locales="en-IN"
        onChange={(event) => console.log(event.target.value)} // "1,23,456.789"
      />
      {/* When requesting a language that may not be supported, such as Balinese, include a fallback language, in this case Indonesian */}
      <InputNumberFormat
        locales={['ban', 'id']}
        onChange={(event) => console.log(event.target.value)} // "123.456,789"
      />
      {/* He nu extension key requests a numbering system, e.g. Chinese decimal */}
      <InputNumberFormat
        locales="zh-Hans-CN-u-nu-hanidec"
        onChange={(event) => console.log(event.target.value)} // "一二三,四五六.七八九"
      />
      {/* Arabic in most Arabic speaking countries uses real Arabic digits */}
      <InputNumberFormat
        locales="ar-EG"
        onChange={(event) => console.log(event.target.value)} // "١٢٣٤٥٦٫٧٨٩"
      />
      {/* German uses comma as decimal separator and period for thousands */}
      <InputNumberFormat
        locales="de-DE"
        format="currency"
        currency="EUR"
        onChange={(event) => console.log(event.target.value)} // "123.456,78 €"
      />
      {/* Formatting with units */}
      <InputNumberFormat
        locales="pt-PT"
        format="unit"
        unit="kilometer-per-hour"
        onChange={(event) => console.log(event.target.value)} // "123 456,789 km/h"
      />
    </>
  );
}

Number format event

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

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

Name	Type	Description
value	string	Formatted value (same as event.target.value).
number	number	The number used for formatting.

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

You can use both the input-number-format 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-number-format event:

import { useState } from 'react';

import { InputNumberFormat, type NumberFormatEventDetail } from '@react-input/number-format';

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

  return <InputNumberFormat value={detail?.value ?? ''} onNumberFormat={(event) => setDetail(event.detail)} />;
}

Integration with custom components

The InputNumberFormat 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 InputNumberFormat component acts as a HOC, adding additional logic to the input element.

Here's how to do it:

import { forwardRef } from 'react';

import { InputNumberFormat } from '@react-input/number-format';

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 InputNumberFormat
export default function App() {
  return <InputNumberFormat component={CustomInput} label="Label for custom component" />;
}

The InputNumberFormat component will not forward properties available only to the InputNumberFormat, 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 InputNumberFormat and pass it as a value to the inputComponent property of the Material UI component.

In this case, the Material UI component expects your component to be wrapped in a forwardRef, where you will need to pass the reference directly to the ref property of the InputNumberFormat component.

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

import { forwardRef } from 'react';

import { InputNumberFormat, type InputNumberFormatProps } from '@react-input/number-format';
import { TextField } from '@mui/material';

// Component with InputNumberFormat
const ForwardedInputNumberFormat = forwardRef<HTMLInputElement, InputNumberFormatProps>((props, forwardedRef) => {
  return <InputNumberFormat ref={forwardedRef} locales="en" maximumFractionDigits={2} {...props} />;
});

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

or using the useNumberFormat hook:

import { useNumberFormat } from '@react-input/number-format';
import { TextField } from '@mui/material';

export default function App() {
  const inputRef = useNumberFormat({ locales: 'en', maximumFractionDigits: 2 });

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

The examples correspond to Material UI version 5. If you are using a different version, please read the Material UI documentation.

Usage with TypeScript

The @react-input/number-format 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 { InputNumberFormat } from '@react-input/number-format';

import type { NumberFormatEventDetail, NumberFormatEvent, NumberFormatEventHandler } from '@react-input/number-format';

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

  // Or `event: NumberFormatEvent`
  const handleNumberFormat: NumberFormatEventHandler = (event) => {
    setDetail(event.detail);
  };

  return <InputNumberFormat onNumberFormat={handleNumberFormat} />;
}

Property type support

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

By default, the InputNumberFormat component is an input element and supports all the attributes supported by the input element. But if the component property was passed, the InputNumberFormat 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 formatting where necessary.

import { InputNumberFormat, type InputNumberFormatProps, type NumberFormatProps } from '@react-input/number-format';

export default function App() {
  // Here, since no `component` property was passed,
  // `InputNumberFormat` returns an `input` element and takes the type:
  // `NumberFormatProps & React.InputHTMLAttributes<HTMLInputElement>` (the same as `InputNumberFormatProps`)
  return <InputNumberFormat />;
}

import { InputNumberFormat, type InputNumberFormatProps, type NumberFormatProps } from '@react-input/number-format';

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

export default function App() {
  // Here, since the `component` property was passed,
  // `InputNumberFormat` returns the CustomInput component and takes the type:
  // `NumberFormatProps & CustomInputProps` (the same as `InputNumberFormatProps<typeof CustomInput>`)
  return <InputNumberFormat component={CustomInput} />;
}

You may run into a situation where you need to pass rest parameters (...rest) to the InputNumberFormat 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 fix this situation and help the InputNumberFormat correctly inject your component's properties, you can pass your component's type directly to the InputNumberFormat component.

import { InputNumberFormat } from '@react-input/number-format';

import { CustomInput } from './CustomInput';

export default function Component(props: any) {
  return <InputNumberFormat<typeof CustomInput> component={CustomInput} {...props} />;
}

Testing and development

To make it easier to work with the library, you will receive corresponding messages in the console when errors occur, which is good during development, but not needed in a production application. To avoid receiving error messages in a production application, make sure that the NODE_ENV variable is set to "production" when building the application.

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.

Utils

@react-input/number-format provides utilities to make things easier when processing a value. You can use them regardless of using the InputNumberFormat component or the useNumberFormat hook.

format

Formats the value using the specified locales and options.

Takes two parameters, where the first is a number or string to format, and the second is an object with options you use when formatting.

The result is exactly the same as the value received from the input. Useful when you need to get a formatted value without raising the input event.

Since InputNumberFormat works exactly like the input element, InputNumberFormat will not change the value outside of the input event for a controlled input, so you may end up in a situation where the input element has a value that does not match the desired format, such as when initializing a value received from a backend (see «Initializing the value» for more details).

format(123456.78, { locales: 'en-IN', format: 'currency', currency: 'USD' });
// returns: "$1,23,456.78"

unformat

Unformats the value using the specified locales.

Takes two parameters, where the first is the value to format, and the second is the locale you are using when formatting. Specifying the locale is required to recognize digits, decimal separator, and minus signs, as they may differ across locales.

Returns a string as the numeric equivalent of the formatted value. Returning a string is due to the fact that a string stores integer and decimal values ​​regardless of their length, unlike a number which has a limit of 2^5. Using a string, you can convert it to a number at your discretion, as well as separate the integer and decimal parts and use the conversion to BigInt.

unformat('$1,23,456.78', 'en-IN');
// returns: "123456.78"

Other packages from @react-input

• @react-input/mask - apply any mask to the input using a provided component or a 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.

You can also support the authors by donating 🪙 to Open Collective:

License

MIT © Nikolay Goncharuk