javascript simulation php function in_array_javascript tips

Array.prototype.S=String.fromCharCode(2); 
Array.prototype.in_array=function(e){ 
  var r=new RegExp(this.S+e+this.S); 
  return (r.test(this.S+this.join(this.S)+this.S)); 
}; 

var arr=new Array(["b",2,"a",4,"test"]); 
arr.in_array('test');//判断 test 字符串是否存在于 arr 数组中，存在返回true 否则false，此处将返回true 

function inArray(needle, haystack) {
  var length = haystack.length;
  for(var i = 0; i < length; i++) {
    if(haystack[i] == needle) return true;
  }
  return false;
}