React-Truncate

Install

$ npm install react-truncate

Usage

import Truncate from 'react-truncate';

// ...

class Foo extends Component {
    render() {
        return (
            <Truncate lines={3} ellipsis={<span>... <a href='/link/to/article'>Read more</a></span>}>
                {longText}
            </Truncate>
        );
    }
}

Hint: (Generally with React) if you want to preserve newlines from plain text, you need to do as follows:

//...
    {text.split('\n').map((line, i, arr) => {
        const line = <span key={i}>{line}</span>;

        if (i === arr.length - 1) {
            return line;
        } else {
            return [line, <br key={i + 'br'} />];
        }
    })}
//...

API

Prop	Type	Default	Description	Example
lines	integer, boolean {false}	`1`	Specifies how many lines of text should be preserved until it gets truncated. `false` and any integer < 1 will result in the text not getting clipped at all.	(`false`, `-1`, `0`), `1`, ...
ellipsis	string, React node	`'…'`	An ellipsis that is added to the end of the text in case it is truncated.	`'...'`, `<span>...</span>`, `<span>... <a href='#' onClick={someHandler}>Read more</a></span>`, `[<span key='some'>Some</span>, <span key='siblings'>siblings<span>]`
children	string, React node		The text to be truncated. Anything that can be evaluated as text.	`'Some text'`, `<p>Some paragraph <a/>with other text-based inline elements<a></p>`, `<span>Some</span><span>siblings</span>`
trimWhitespace	boolean	`false`	If `true`, whitespace will be removed from before the ellipsis (e.g. `words ...` will become `words...` instead)
width	number	`0`	If not `0`, the calculation of the content will be based on this number.
onTruncate	function		Gets invoked on each render. Gets called with `true` when text got truncated and ellipsis was injected, and with `false` otherwise.	`isTruncated => isTruncated !== this.state.isTruncated && this.setState({ isTruncated })`

Known issues

Resize content when the size of parent container changed (use the width property or call ref.onResize()). See issue
Text exceeding horizontal boundaries when "viewport" meta tag is not set accordingly for mobile devices (font boosting leads to wrong calculations). See issue
Output in plain text only - no support for markup/HTML. See issue
Wrong line breaks when custom font is loading after the component has rendered. See issue
No support for letter spacing / word spacing. See issue

Integrated example for toggling "read more" text

import React, { Component } from 'react';
import PropTypes from 'prop-types';
import Truncate from 'react-truncate';

class ReadMore extends Component {
    constructor(...args) {
        super(...args);

        this.state = {
            expanded: false,
            truncated: false
        };

        this.handleTruncate = this.handleTruncate.bind(this);
        this.toggleLines = this.toggleLines.bind(this);
    }

    handleTruncate(truncated) {
        if (this.state.truncated !== truncated) {
            this.setState({
                truncated
            });
        }
    }

    toggleLines(event) {
        event.preventDefault();

        this.setState({
            expanded: !this.state.expanded
        });
    }

    render() {
        const {
            children,
            more,
            less,
            lines
        } = this.props;

        const {
            expanded,
            truncated
        } = this.state;

        return (
            <div>
                <Truncate
                    lines={!expanded && lines}
                    ellipsis={(
                        <span>... <a href='#' onClick={this.toggleLines}>{more}</a></span>
                    )}
                    onTruncate={this.handleTruncate}
                >
                    {children}
                </Truncate>
                {!truncated && expanded && (
                    <span> <a href='#' onClick={this.toggleLines}>{less}</a></span>
                )}
            </div>
        );
    }
}

ReadMore.defaultProps = {
    lines: 3,
    more: 'Read more',
    less: 'Show less'
};

ReadMore.propTypes = {
    children: PropTypes.node.isRequired,
    lines: PropTypes.number,
    less: PropTypes.string,
    more: PropTypes.string
};

export default ReadMore;

Developing

Install system libraries needed for development dependencies

https://github.com/Automattic/node-canvas#installation

Install development dependencies

$ npm install

Run tests

$ npm test

Run code linter

$ npm run lint

Compile to ES5 from /src to /lib

$ npm run compile