each function does not check object is iterable

[[email protected]…]

$.each(obj, function(index, value){
    alert(index);
});

If obj is not an Array or not a String or not an Object, it will raise an error like "Uncaught TypeError: Cannot read property 'length' of undefined ".

I think before define "length=object.length" will check object type.

[dmethvin]

That would make debugging harder if we covered up mistakes. Pass in valid arguments.