Question

Let’s take a look at this code:

var mainFunction = function() {
  altFunction.apply(null, arguments);
}

The arguments that are passed to mainFunction are dynamic — they can be 4 or 10, doesn’t matter. However, I have to pass them through to altFunction AND I have to add an EXTRA argument to the argument list.

I have tried this:

var mainFunction = function() {
  var mainArguments = arguments;
  mainArguments[mainArguments.length] = 'extra data'; // not +1 since length returns "human" count.

  altFunction.apply(null, mainArguments);
}

But that does not seem to work. How can I do this?

Answer 1

arguments is not a pure array. You need to make a normal array out of it:

var mainArguments = Array.prototype.slice.call(arguments);
mainArguments.push("extra data");