extjs beforestaterestore in gridfilters

In extjs, gridFilters, we h开发者_运维问答ave:

grid.on({
scope: this,
beforestaterestore: this.applyState,

I am unable to understand what exactly is the beforestaterestore doing?

The beforestaterestore event is fired before a Grid is loaded, assuming that the stateful config option was used when creating the Grid.

The code that you've listed will call the Grid's applyState method when this event fires, which will copy properties from the state provider to the Grid object.

I would strongly advise taking a look at the ExtJS Documentation for the Grid Panel for more information.