if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(obj, start) {
     for (var i = (start || 0), j = this.length; i < j; i++) {
       if (this[i] === obj) { return i; }
     }
     return -1;
  }
}
if (!String.prototype.contains) {
  String.prototype.contains = function (arg) {
    return !!~this.indexOf(arg);
  };
}

Enter two strings and check if Strign 1 contains String 2.<br> <br> String 1: <input id="foo" type="text" value="a quick brown fox jumps over">     <br> String 2: <input id="bar" type="text" value="fox jumps">    <br><br> <button onclick="checkstring()">Click to check if String 1 contains String 2</button> <script> if (!Array.prototype.indexOf) {     Array.prototype.indexOf = function(obj, start) {          for (var i = (start || 0), j = this.length; i < j; i++) {              if (this[i] === obj) { return i; }          }          return -1;     } } if (!String.prototype.contains) {     String.prototype.contains = function (arg) {         return !!~this.indexOf(arg);     }; } function checkstring() {     var foo = document.getElementById("foo").value;     var bar = document.getElementById("bar").value;     alert(foo.contains(bar)); } </script>