Difference between if (var.length >0){} and if (var){}

Question

In javascript is there a difference between using

if (foo.length > 0) {
//run code involving foo
}

and

if (foo) {
//run code involving foo
}

If so, could someone please explain the difference and an example where they would not be the same?

Answer 1

Here's an example where they are not the same:

var x = [];
alert(x? 'yes' : 'no'); // displays "yes"
alert((x.length > 0)? 'yes' : 'no'); // displays "no"