Question

My JavaScript code is barely an Ajax request that expects XML to be returned from back-end. The back-end can return execute_callback as one of XML tags like this:

<?xml version="1.0" encoding="windows-1251"?>
<response>
    <execute_callback>
        <function_name>someFunction</function_name>
    </execute_callback>
</response>

And everything is okay as far as you know the exact number of parameters this callback expects. But what if the back-end has returned

<?xml version="1.0" encoding="windows-1251"?>
<response>
    <execute_callback>
        <function_name>someFunction</function_name>
        <param>10.2</param>
        <param>some_text</param>
    </execute_callback>
    <execute_callback>
        <function_name>otherFunction</function_name>
        <param>{ x: 1, y: 2 }</param>
    </execute_callback>
</response>

How do I now pass parameters 10.2 and ‘some_text’ to someFunction and JSON { x: 1, y: 2 } to otherFunction?

I know an ugly solution (using function’s arguments), but I am looking for a pretty one.

And before I forget: don’t parse the XML for me – I can do that on my own 🙂 All I need is somewhat of a trick to pass an arbitrary number of arguments to a function in JavaScript. If you know Python, I want:

def somefunc(x, y):
    print x, y
args = { 'x' : 1, 'y' : 2 }
somefunc(**args)

but in JavaScript.

Answer 1

You could refer to Function.apply. Assuming the callback functions are declared in global object (window in browser).

var callback_function = window[function_name];
if (callback_function) { // prevent from calling undefined functions
    callback_function.apply(window, params);  // params is an array holding all parameters
}