Question

The following piece of code from the jQuery source caught my eye (line 7716 from the latest revision bit.ly/jqsource):

        send: function( _, callback ) {

            script = document.createElement( "script" );

            script.async = "async";

// BLA BLA BLA
        }

At no point is the named parameter _ used. It seems this is to force callback to be arguments[1] instead of arguments[0]. Why would that be useful?

Answer 1

It’s merely a convention adopted to reference non-used parameters.

If they didn’t have some parameter name there, the only way to get the second argument would be to do:

arguments[1];

…and that would bring us back to your earlier question about JSLint complaining about static reference to individual members of the arguments object.