Will this test to check if an element has an attribute work?

Question

Here is my code:

hasAttr = new function(tag, attrName) {
    return (tag.attrName)
}

Will this code work? I can't test it now because I cannot acces jsfiddle and jsbin but Down For Everyone or Just Me? says something else.

1. jsFiddle Down For Everyone or Just Me
2. jsBin Down For Everyone or Just Me

Example usage:

JavaScript:

alert(hasAttr("div", "id"))

HTML:

<div id="header"></div>

Expected:

(In alert box)
    true
                OK

Can someone test it for me?

If it doesn't work, how should I code it?

I want hasAttr to return true or false.

I will be open to code optimization, cleaner code etc.

Thanks in advance!

Answer 1

To check if an HTML element has an attribute, you should use hasAttribute. If you have to support IE6 and IE7, check its existence using [name].

Given that, the implementation of hasAttr would be something like this:

hasAttr = function(tag, attrName) {
    return tag.hasAttribute ? tag.hasAttribute(attrName)
                            : tag[attrName] !== undefined;
}

Answer 2

Testing JavaScript code in jsFiddle to make sure it works is suicide. The difficult part about JavaScript is really cross-browser compatibility, which means you just can't just test in one browser to say it works.

That being said, the name hasAttr makes me think that you want to return true/false, which is not what you're doing. You should use DOM's element.hasAttribute(), which already implements what you're trying to do. It's DOM 1, so it's safe to use and will work in any browser supporting JavaScript.

By the way, why are you using this funky syntax to create your function? Is there a good reason not to use function hasAttribute() { ... }?

(You should accept seand's answer, though, I didn't know it wasn't supported until IE 8. You should also consider using something like jQuery which will help you avoid mistakes like that.)