Backbone.js: correct way of filtering a collection?

Question

The current method I\'m using is to filter a collection, which returns an array, and use

collection.reset(array)

to re-populate it. However

Answer 1

You could create a collection as a property of the main collection reflecting the state of the filters:

var C = Backbone.Collection.extend({
    initialize: function (models) {
        this.filtered = new Backbone.Collection(models);
        this.on('add', this.refilter);
        this.on('remove', this.refilter);
    },

    filterBy: function (params){
        var filteredColl = this.filter(function(item){
          // ...
        });

        this.filtered.params = params;
        this.filtered.reset(filteredColl);
    },

    refilter: function() {
        this.filterBy(this.filtered.params);
    }
});

The parent collection keeps its models whatever filters you applied, and you bind to the filtered collection to know when a change has occurred. Binding internally on the add and remove events lets you reapply the filter. See http://jsfiddle.net/dQr7X/ for a demo.