Question

Normally I would set a functions variables with something like this:

var width = null;
var height = null;

if(options) {
    if(options.width) width = options.width;
    if(options.height) height = options.height;
}

Is there a way to simplify this with something like:

var width = null;
var height = null;

if(options) {
    for(var val in options) {
        val = options[val];
    }
}

In this simple example it doesn’t seem like a big benefit, but in a situation where I have a multitude of variables to set with values from a single object (in such a way that say…ajax does it), it would be much easier to just loop the object and do it that way.

Answer 1

Not directly. If you want to attach things to the global namespace (window), you could write something like this:

if (options) {
  for(var val in options) {
    window[val] = options[val];
  }
}

…but you would generally want to avoid cluttering up window unless absolutely necessary. A commonly used alternative would be to create an object for holding default options, and simply overwrite them as new options are provided:

var defaults = {
  height: 0,
  width: 0
}

if (options) {
  for(var val in options) {
    defaults[val] = options[val];
  }
}

// use values now stored in `defaults`
console.log(defaults.height);