An input component that abides by configurable formatting and constraint rules

FormattedInput takes a value and ensures that user input conforms to some specified rules. Formatted input instances can have their length limited, as well as having a pattern enforced for their entry. As the user types, changes to the value are forced through the provided pattern and any sections that are invalid are simply stripped. What is returned from the component is a pattern-matched string.

This is useful for custom inputs that are designed to take values of a certain type, often mapping to real world information like credit card details or dates.

To install, simply run npm install @buttercup/react-formatted-input --save or yarn add @buttercup/react-formatted-input.

You can run the Storybook to test the component in your browser, by executing npm run storybook.

Import the FormattedInput class and just drop it in:

import { FormattedInput } from "@buttercup/react-formatted-input";
import React, { Component } from "react";

export default class MyForm extends Component {

    constructor(props) {
        super(props);
        this.state = {
            idNumber: ""
        };
    }

    render() {
        const idPattern = [
            { char: /\d/, repeat: 3 },
            { exactly: "-" },
            { char: /\d/, repeat: 2 },
            { char: /[a-z]/i }
        ];
        return (
            <form>
                <FormattedInput
                    className="formatted-input"
                    format={idPattern}
                    value={this.state.idNumber}
                    onChange={(formattedValue, raw) => { this.state.idNumber = formattedValue; }}
                    placeholder="ID in format: NNN-NNL"
                    />
            </form>
        );
    }

}

There is also a FormattedText class which simply outputs a text node:

import React from "react";
import { FormattedText } from "@buttercup/react-formatted-input";

// MM/YYYY
const DateFormat = [
    { char: /[01]/, repeat: 1 },
    { char: /\d/, repeat: 1 },
    { exactly: "/" },
    { char: /2/, repeat: 1 },
    { char: /\d/, repeat: 3 }
];

const MyComponent = () => (
    <span>
        <FormattedText value="01/2019" format={DateFormat} />
    </span>
);

You can also import just the format function:

import { format } from "@buttercup/react-formatted-input";

const USPhoneNumberFormat = [
    { char: /\d/, repeat: 3 },
    { exactly: "-" },
    { char: /\d/, repeat: 3 },
    { exactly: "-" },
    { char: /\d/, repeat: 4 }
];

const { formatted, raw } = format("2025550199", USPhoneNumberFormat);
// formatted = 202-555-0199
// raw = 2025550199

As Regular Expression instances don't serialise, it's possible to use a string or array to describe the pattern:

const format1 = [{ char: "\\w", repeat: 5 }];

const format2 = [{ char: ["[a-f0-9]", "i"], repeat: 5 }];

The second value in the array is the flag string for the RegExp constructor.

Some presets are available in the source/presets.js file that might be used like so:

import { FormattedInput, Presets } from "@buttercup/react-formatted-input";
import React, { Component } from "react";

export default class MyForm extends Component {

    render() {
        return (
            <form>
                <FormattedInput
                    format={Presets.CreditCard}
                    value={this.state.creditCardNo}
                    />
                <FormattedInput
                    format={Presets.CreditCardDate}
                    value={this.state.creditCardValidFrom}
                    />
                <FormattedInput
                    format={Presets.CreditCardDate}
                    value={this.state.creditCardExpiry}
                    />
            </form>
        );
    }

}

The FormattedInput component can be used without any props, of course, but you might want some of these for it to be useful:

The initialisation value for the formatted input. This value is still run through the formatting process, so it is possible that the applied value is different to the one provided.

The format is a collection of patterns and delimiters that control what values can be entered. By default there is no format (so any input is allowed), but it can be set to an array of objects that are used to process the value upon every change:

• Character match groups: A character match (char) is a regular expression designed to match just 1 character. It may also contain a repeat property to specify how many characters this pattern should match. repeat defaults to 1 if not specified. For example, { char: /\d/ } will match exactly 1 number, whereas { char: /-/, repeat: 3 } will match 3 dashes.
• Exact groups: An exact group represents a string or character that must come next in the value. It is used to specify mandatory delimiters in the value. For instance, { exactly: "." } will enforce that a period appears next in the value. Exact groups also support the repeat property. Characters added using exact groups do not appear in raw values.

When used in combination together, complex values like credit-card numbers can be easily represented:

[
    { char: /\d/, repeat: 4 },
    { exactly: "-" },
    { char: /\d/, repeat: 4 },
    { exactly: "-" },
    { char: /\d/, repeat: 4 },
    { exactly: "-" },
    { char: /\d/, repeat: 4 }
]

Or even the expiry date of such a credit card:

[
    { char: /[01]/ },  // month, 2 digits
    { char: /[0-9]/ }, // "
    { exactly: "/" },
    { char: /2/ },                  // year, 4 digits
    { char: /[0-9]/, repeat: 3 }    // "
]

A callback function for when the value changes. The function receives 2 parameters: the new formatted value and the new raw value, respectively. The function is only called if the formatted value differs from the last one.

The input type to use (defaults to "text"). The type "password" is also supported, but this disables formatting.

Formatted input instances pass through these props to the underlying <input> element.