querySelector to find label in pure JS

Question

Strictly using JS, I want to select a label element and add a class.

document.querySelector('[for=foobar]').className = "foo";

What should go in the querySelector to find <label for="foobar">?

The error I'm getting is Uncaught SyntaxError: Failed to execute query: '[for=foobar]' is not a valid selector.

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Ok, I actually solved it by adding quotes around foobar, so it reads:

document.querySelector('[for="foobar"]').className = "foo";

Answer 1

If you're looking for a <label> tag specifically, you would use:

document.querySelector('label[for="foobar"]').className = "foo";

The selector that you have will select the first element of any tag that has the given for attribute.

Here's a fiddle to demonstrate: http://jsfiddle.net/bryanjamesross/f53A4/