Single quotes in JavaScript object literal

Question

I'm looking at the Google Maps API tutorial, and I see this:

<script type="text/javascript" 
        src="http://www.google.com/jsapi?autoload={'modules':[{name:'maps', version:3, other_params:'sensor=false'}]}"></script>

Why is modules wrapped in single quotes?

Answer 1

It's a good practice to wrap keys in quotes, even though not strictly required, in order to avoid the possibility of conflicts with JavaScript reserved words.

Imagine if you had class instead of modules - class happens to be a reserved word in JavaScript, even though it is not actually used in the current specification.

Answer 2

In fact, in most JSON implementations (because it's actually a JSON string), like jQuery's getJSON, it's obligatory to put all strings, whether they represent values or properties, within double-quotes.