Array.prototype.in_array = function(e)
{
for(i=0;i<this.length;i++)
{
if(this[i] == e)
return true;
}
return false;
}

Array.prototype.in_array = function(e)
{
for(i=0;i<this.length && this[i]!=e;i++);
return !(i==this.length);
}

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 aa = new Array(1,2,'aa','bbb',4,5);
alert(aa.in_array(3));
alert(aa.in_array('aa'));