gistfile1.js

String.prototype.split = function (r, limit) {
  var s = String(this),
      last = null,
      lastIndex = null,
      a = [];
  limit = (limit === undefined ? -1 : limit) >>> 0;
  if (!limit) {
    return a;
  }
  if (r === undefined) {
    return [s];
  }
  if (Object.prototype.toString.call(r) === '[object RegExp]') {
    r = new RegExp(r.source, (r.multiline ? 'm' : '') + (r.ignoreCase ? 'i' : '') + 'g');
  } else {
    r = new RegExp(String(r).replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&"), 'g');
  }
  if (s === '') {
    return r.test('') ? [] : [''];
  }
  try {
    s.replace(r, function (p) {
      function push(x) {
        a.push(x);
        limit -= 1;
        if (!limit) {
          throw a;
        }
      }
      var length = arguments.length,
          index = arguments[length - 2],
          i;
      if (lastIndex !== index && !(!p && (last === index || index === 0 || index === s.length))) {
        push(s.slice(last || 0, index));
        last = index + p.length;
        lastIndex = index;
        for (i = 1; i < length - 2; i += 1) {
          push(arguments[i]);
        }
      }
    });
  } catch (e) {
    if (e !== a) {
      throw e;
    }
  }
  if (lastIndex !== s.length && limit) {
    a.push(s.slice(last || 0));
  }
  return a;
}

An alternative implementation: https://gist.github.com/slevithan/2048056