How can I pre-set arguments in JavaScript function call? (Partial Function Application)

Question

I am trying to write a JavaScript function that will return its first argument(function) with all the rest of its arguments as preset parameters to that function.

So

Answer 1

You could use Function.prototype.bind() for this. It's an ES5 addition.

In addition to the common usecase of setting a function's context (this value), it can also set partial arguments.

function out(a, b) {
  document.write(a + " " + b);
}

function setter(func) {
  return func.bind.apply(func, [window].concat([].slice.call(arguments).slice(1)));
}

setter(out, "hello")("world");
setter(out, "hello", "world")();

My setter function is actually very simple. The longest part is just getting the list of arguments. I'll break up the code like this:

func.bind.apply(func, [window].concat([].slice.call(arguments).slice(1)))
func.bind.apply(                                                        )  // need to use apply to pass multiple arguments as an array to bind()
                func,                                                      // apply needs a context to be run in
                      [window].concat(                                 )   // pass an array of arguments to bind(), starting with window, to be the global context
                                      [].slice.call(arguments).slice(1)    // convert the arguments list to an array, and chop off the initial value

It's supported in these browsers: Chrome 7+, Firefox 4+, IE9+. MDN (linked at the beginning) has a polyfill though.