Ext.apply and Ext.applyIf

In case you missed it, last weekend Jay Garcia released his third screencast in which he explains Ext.apply.

Here is the video, a short 7 and something minutes long, which is a fresh alternative of reading plain blog posts. :-)

Jay actually mentions a firebug bug which I wasn't aware of but which I encountered just this week after learning about it in his screencast. The bug is that the properties of an object you are inspecting (after clicking on the your object which is printed to your console via console.log(object) or console.info(object)) might not be the actual current ones. The work-around is to print directly the property you want to inspect via console.log(object.property).

If you're a little confused about the defaults (third) parameter of Ext.apply, then just think of it as you would write the the following

Ext.apply(receiver, defaults);
Ext.apply(receiver, source);

// is the same as
Ext.apply(receiver, source, defaults);

Also note that there is an Ext.applyIf method (without a third parameter) which only assigns properties/attributes to the receiver object if they aren't existing in the receiver object yet.

And as a small extra here's a real-world example of using Ext.apply which I implemented this week:

onBeforeLoad: function(store, options) {
  options.params = options.params || {};
  this.cleanParams(options.params);  
  var params = this.buildQuery(this.getFilterData());
  if (store.lastOptions && store.lastOptions.params) {
    options.params = Ext.apply(store.lastOptions.params, options.params);
  }
  Ext.apply(options.params, params);
}

I'm overwriting here the onBeforeLoad method from the excellent Ext.ux.GridFilter extension which is executed every time before the store is loading.
So if you load the store the first time via store.load({params: {start: 0, limit: 50}}), it will resend these parameters when the store is reloaded after you changed your filter values or after you manually executed store.load() after you saved changes to your EditorGridPanel for example. Moreover, the lastOptions params will be overwritten when you switch to the next page via your PagingToolbar, which calls something like store.load({params: {start: 50, limit: 50}}).