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copied!<pre><code>/** Function that count occurrences of a substring in a string; * @param {String} string The string * @param {String} subString The sub string to search for * @param {Boolean} [allowOverlapping] Optional. (Default:false) * * @author Vitim.us https://gist.github.com/victornpb/7736865 * @see Unit Test https://jsfiddle.net/Victornpb/5axuh96u/ * @see http://stackoverflow.com/questions/4009756/how-to-count-string-occurrence-in-string/7924240#7924240 */ function occurrences(string, subString, allowOverlapping) { string += ""; subString += ""; if (subString.length <= 0) return (string.length + 1); var n = 0, pos = 0, step = allowOverlapping ? 1 : subString.length; while (true) { pos = string.indexOf(subString, pos); if (pos >= 0) { ++n; pos += step; } else break; } return n; } </code></pre> <h2>Usage</h2> <pre><code>occurrences("foofoofoo", "bar"); //0 occurrences("foofoofoo", "foo"); //3 occurrences("foofoofoo", "foofoo"); //1 </code></pre> <h3>allowOverlapping</h3> <pre><code>occurrences("foofoofoo", "foofoo", true); //2 </code></pre> <p>Matches:</p> <pre><code> foofoofoo 1 `----´ 2 `----´ </code></pre> <h2>Unit Test</h2> <ul> <li><a href="https://jsfiddle.net/Victornpb/5axuh96u/" rel="noreferrer">https://jsfiddle.net/Victornpb/5axuh96u/</a></li> </ul> <h2>Benchmark</h2> <blockquote> <p>I've made a benchmark test and my function is more then 10 times faster then the regexp match function posted by gumbo. In my test string is 25 chars length. with 2 occurences of the character 'o'. I executed 1 000 000 times in Safari.</p> <p><strong>Safari 5.1</strong></p> <p>Benchmark> Total time execution: 5617 ms (regexp)</p> <p>Benchmark> Total time execution: 881 ms (my function 6.4x faster)</p> <p><strong>Firefox 4</strong></p> <p>Benchmark> Total time execution: 8547 ms (Rexexp)</p> <p>Benchmark> Total time execution: 634 ms (my function 13.5x faster)</p> <hr> <p>Edit: changes I've made</p> <ul> <li><p>cached substring length</p></li> <li><p>added type-casting to string.</p></li> <li><p>added optional 'allowOverlapping' parameter</p></li> <li><p>fixed correct output for "" empty substring case.</p></li> </ul> </blockquote> Gist <ul> <li><a href="https://gist.github.com/victornpb/7736865" rel="noreferrer">https://gist.github.com/victornpb/7736865</a></li> </ul>

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