emoji.js

/** @jsx React.DOM */

define([
  'react',
  'modernizr',
  'punycode'
], function(React, Modernizr, punycode) {

  /**
   * Replaces the emojis in a text string with <img> tags
   */

  var isEmojiCode = function(charCode) {
    return (
      ( charCode >= 0x1F300 && charCode <= 0x1F5FF ) ||
      ( charCode >= 0x1F600 && charCode <= 0x1F64F ) ||
      ( charCode >= 0x1F680 && charCode <= 0x1F6FF ) ||
      ( charCode >= 0x2600 && charCode <= 0x26FF )
    );
  };

  var emojiTransform = function(text) {
    var decoded = punycode.ucs2.decode(text);

    var entries = [];
    decoded.forEach(function(charCode, idx) {
      if ( isEmojiCode(charCode) ) {
        // emoji char encountered, insert img tag
        var hexCode = charCode.toString(16);
        entries.push(
          <img src={"/w/images/emoji/" + hexCode + ".png"} key={idx} />
        );
      } else {
        var char = punycode.ucs2.encode([charCode]);

        var lastIdx = entries.length - 1;
        if ( typeof entries[lastIdx] === 'string' ) {
          entries[lastIdx] += char;
        } else {
          entries.push(char);
        }
      }
    });

    return entries;
  };

  var Emojify = React.createClass({

    propTypes: {
      text: React.PropTypes.string.isRequired
    },

    shouldComponentUpdate: function(nextProps) {
      return nextProps.text !== this.props.text;
    },

    render: function() {
      var emojifiedText = !Modernizr.emoji ? emojiTransform(this.props.text) : this.props.text;

      return (
        <span>{emojifiedText}</span>
      );
    }

  });

  return Emojify;

});

Thanks, it was helpful.

For the reference, here is code for GitHub's hosted set of emoji:

<img src={"https://assets-cdn.github.com/images/icons/emoji/unicode/" + hexCode + ".png"} key={idx} />

Example https://assets-cdn.github.com/images/icons/emoji/unicode/1f42f.png

Thanks for this!