Question

I created a popup function and recently changed the format from this:

createPopUp('My Popup',600,200);

to this method:

createPopUp({ title: 'My Popup', width: 600, height: 200 });

I only want to use the values if they exist, so I am currently doing this:

function createPopUp(config){

  if (typeof config.title != 'undefined'){
    var theTitle = title;
  } else {
    var theTitle = 'Untitled';
  }

}

However this seems very messy so I have been looking for a more efficient way of checking for incoming parameters or setting default values and a nudge in the right direction would be much appreciated.

Answer 1

You can extend a default set of properties like this:

var defaults = {
    title: 'Untitled',
    width: 100,
    height: 100
}

function createPopUp(config)
{
    var opts = {}

    for (var k in defaults) {
        opts[k] = config[k] || defaults[k];
        // sometimes falsy values should be allowed to override defaults
        // in that case, use this instead:
        // opts[k] = typeof config[k] != 'undefined' ? config[k] : defaults[k]
    }

    // opts contains values from defaults where config doesn't have them
}

jQuery has a handy $.extend() for this purpose, but you didn’t tag your post as such.