Question

I found this in a jQuery file:

xxx.css({ 'float' : 'right' });

What do the curly braces do?

Answer 1

In your case it is an object passed to your css function.

myObj={} // a blank object

Here you can use this too

myObj={'float' : 'right'}
xxx.css(myObj);

Here is another example of object

var myObj={
    'varOne':'One',
    'methodOne':function(){ alert('methodOne has been called!')}        
}
myObj.methodOne();​ // It will alert 'methodOne has been called!'

A fiddle is here.