javascript - Replace a list of emoticons with their images

Question

I have an array with:

emoticons = {
   ':-)' : 'smile1.gif',
   ':)'  : 'smile2.gif',
   ':D'  : 'smile3.gif'     
}

then i have a variabile with the text.

var text = 'this is a simple test :)';

and a variable with the url of the website

var url = "http://www.domain.com/";

How to write a function that replace the symbols with their images?

The <img> tag result should be:

<img src="http://www.domain.com/simple2.gif" />

(I have to concatenate the url varible to the name of the image).

THank you very much!

Answer 1

Another approach:

function replaceEmoticons(text) {
  var emoticons = {
    ':-)' : 'smile1.gif',
    ':)'  : 'smile2.gif',
    ':D'  : 'smile3.gif'
  }, url = "http://www.domain.com/";
  // a simple regex to match the characters used in the emoticons
  return text.replace(/[:-)D]+/g, function (match) {
    return typeof emoticons[match] != 'undefined' ?
           '<img src="'+url+emoticons[match]+'"/>' :
           match;
  });
}

replaceEmoticons('this is a simple test :)');
// "this is a simple test <img src="http://www.domain.com/smile2.gif"/>"

Edit: @pepkin88 made a really good suggestion, build the regular expression based on the property names of the emoticons object.

It can be easily done, but we have to escape meta-characters if we want this to work properly.

The escaped patterns are stored on an array, that is later used to build the regular expression using the RegExp constructor, by basically joining all the patterns separated with the | metacharacter.

function replaceEmoticons(text) {
  var emoticons = {
    ':-)' : 'smile1.gif',
    ':)'  : 'smile2.gif',
    ':D'  : 'smile3.gif',
    ':-|'  : 'smile4.gif'
  }, url = "http://www.domain.com/", patterns = [],
     metachars = /[[]{}()*+?.\|^$-,&#s]/g;

  // build a regex pattern for each defined property
  for (var i in emoticons) {
    if (emoticons.hasOwnProperty(i)){ // escape metacharacters
      patterns.push('('+i.replace(metachars, "\$&")+')');
    }
  }

  // build the regular expression and replace
  return text.replace(new RegExp(patterns.join('|'),'g'), function (match) {
    return typeof emoticons[match] != 'undefined' ?
           '<img src="'+url+emoticons[match]+'"/>' :
           match;
  });
}

replaceEmoticons('this is a simple test :-) :-| :D :)');