Answer by Vitim.us for How to count string occurrence in string?

/** 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 https://stackoverflow.com/a/7924240/938822 */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;}

Usage

occurrences("foofoofoo", "bar"); //0occurrences("foofoofoo", "foo"); //3occurrences("foofoofoo", "foofoo"); //1

allowOverlapping

occurrences("foofoofoo", "foofoo", true); //2

Matches:

  foofoofoo1 `----´2    `----´

Unit Test

• https://jsfiddle.net/Victornpb/5axuh96u/

Benchmark

I've made a benchmark test and my function is more then 10 timesfaster then the regexp match function posted by gumbo. In my teststring is 25 chars length. with 2 occurences of the character 'o'. Iexecuted 1 000 000 times in Safari.

Safari 5.1

Benchmark> Total time execution: 5617 ms (regexp)

Benchmark> Total time execution: 881 ms (my function 6.4x faster)

Firefox 4

Benchmark> Total time execution: 8547 ms (Rexexp)

Benchmark> Total time execution: 634 ms (my function 13.5x faster)

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Edit: changes I've made

• cached substring length

• added type-casting to string.

• added optional 'allowOverlapping' parameter

• fixed correct output for "" empty substring case.

Gist

• https://gist.github.com/victornpb/7736865