String search functions in Javascript, tests with and without Regex. Summary: Regex is faster. http://jsperf.com/javascript-find-all

javascript-find-all.js

// http://jsperf.com/javascript-find-all

function indexes(str, find) {
  var result = [];
  for(i=0;i<str.length; ++i) {
    if (str.substring(i, i + find.length) == find) {
      result.push(i);
    }
  }
  return result;
}

console.log(indexes("I learned to play the Ukulele in Lebanon.", "le"));

function indexes2(str, find) {
    var regex = new RegExp(find,"g");
    var result, 
        indices = [];
    while ( (result = regex.exec(str)) ) {
        indices.push(result.index);
    }
    return indices;
}

console.log(indexes2("I learned to play the Ukulele in Lebanon.", "le"));