Extending incompatible methods in IE such as contains startWith and so on

 
 
String.prototype.startWith=function(str){ 
if(str==null||str==""||this.length==0||str.length>this.length) 
return false; 
if(this.substr(0,str.length)==str) 
return true; 
else 
return false; 
return true; 
}; 


 
Array.prototype.contains = function(item){ 
return RegExp("\b"+item+"\b").test(this); 
}; 


 
Array.prototype.indexOf = function(val){ 
var value = this; 
for(var i =0; i < value.length; i++){ 
if(value[i] == val) return i; 
} 
return -1; 
};