Question

I’m struggling with some jQuery code I’m working on, and I’ve narrowed down the problem to this simple example that doesn’t behave as I would expect it too:

jsFiddle:
http://jsfiddle.net/HypYT/

---

HTML

<div id="a">a: <span>A</span></div>
<div id="b">b: <span>B</span></div>​

jQuery

jQuery.each( ["#a", "#b"], function(){
    alert(this);    // alerts "#a" and "#b"
    $(this).hide(); //not working
    $('#b').hide(); //working
});​

---

Anyone have any insight what’s going on here?

Answer 1

If a function is called on a string (or other primitive), this becomes a boxed object.
typeof this will therefore return "object", not "string".
This breaks jQuery. (no pun intended)

You can fix this by forcing it back to a string primitive:

$(String(this)).hide()

You can fix this for arbitrary primitives by writing

var self = this.constructor(this);

However, using the second argument passed to .each() will be faster, because it will avoid boxing in the first place.