Finding Value In Array

This is just some functionality missing in the Array object that I'd find very useful...

Array.prototype.inArray=function(oObject){
for(var i in this){
if(this[i]===oObject){
return true;
}
}
return false;
}

to use:

var oObj=new Object();
var aArray=[1,oObj,"string"];
aArray.inArray(1); // returns true
aArray.inArray(oObj); // returns true
aArray.inArray("string"); // returns true
aArray.inArray(2); // returns false