Backbone.Index

Simple, dynamic indexes for greasy-fast filtering of collections

It useful for:

• Filtering collection with selected keys more than 5 times
• Using query instead of Backbone.Collection's default where if you need to filter to values in an array

Installation

$ bower install backbone-index --save

or include index.js with script tag.

Example

var Users = Backbone.Collection.extend({});

// Apply Backbone.Index to Collection
Backbone.Index(Users);

var users = new Users([
  { id: 1, companyId: 1, officeId: 1, name: 'John'  },
  { id: 2, companyId: 1, officeId: 1, name: 'Peter' },
  { id: 3, companyId: 1, officeId: 2, name: 'Bret'  },
  { id: 4, companyId: 2, officeId: 5, name: 'Tom'   },
  { id: 5, companyId: 1, officeId: 3, name: 'Keit'  },
  { id: 6, companyId: 1, officeId: 2, name: 'Anna'  },
  { id: 7, companyId: 2, officeId: 3, name: 'Helen' },
  { id: 8, companyId: 3, officeId: 1, name: 'Maria' },
  { id: 9, companyId: 2, officeId: 5, name: 'Adam'  }
]);

users.where({ companyId: 1 }); // => [Array(5)] ~ 0.16ms

// Subsequent requests use the index to return values much faster than the
// initial request
_.times(100, function() {
  users.where({ companyId: _.random(1, 3) });
}); // => ~ 0.37ms

How it works

When you run a query the first time, Backbone.Index runs a groupBy method and generates an index for all possible combinations of the value for selected keys.

The second time, it uses the index, and does not need to do any filtering. To ensure a correct dataset, Backbone.Index also subscribes to add, change and remove Backbone events.

API

Backbone.Index(Collection)

Apply index functionality to selected collection.

collection.where(attributes, [first])

Alias: collection.query.

Same semantic as Backbone.Collection::where.

Second boolean optional argument is for cases when you need only one value, it's similar to Backbone.Collection::findWhere.

As a query parameters you can pass values, arrays of values, or arrays of Backbone.Models.

users.where({ companyId: 2, officeId: 2 });
users.where({ companyId: 1, officeId: [1, 3] });
users.where({ officeId: [office1, office2] });