code: function contains(origin, search, start) {
    'use strict';
    if (typeof start !== 'number') {
      start = 0;
    }
    if (start + search.length > origin.length) {
      return false;
    } else {
      return origin.indexOf(search, start) !== -1;
    }
  }
docs: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/includes