Efficiently loading components in Angular using browserify with lazy loading

Question

Efficiently loading components in Angular using browserify with lazy loading

As I work on developing the architecture of a complex application with Angular, I have started with the angular-seed project which seems to be a solid starting point. However, one issue that concerns me is how Angular apps tend to load everything upfront by nature, making it difficult to implement lazy loading using script loaders.

Coming from a background in backbone.js, where I used require.js for lazy loading based on router callbacks, handling routes in Angular feels somewhat different. The code snippet below demonstrates how routes are typically defined:

// Declare app level module which depends on views, and components
angular.module('myApp', [
  'ngRoute'
]).
config(['$routeProvider', function($routeProvider) {
  $routeProvider.when({templateURL:'../tmpl.html',controller:'view1Ctrl'})
.when({templateURL:'../tmpl.html',controller:'view1Ctrl'})
.otherwise({redirectTo: '/view1'});
}]);

In this line

$routeProvider.when({templateURL:'../tmpl.html',controller:'view1Ctrl'})

, my goal is to find a way to lazily load both the controller and the template. I considered using something like:

$routeProvider.when({templateURL:'../tmpl.html',controller:require('view1Ctrl'})

with browserify, but it doesn't feel like a clean solution even with require included. I know similar questions have been raised on SO before, but I am yet to find a definitive answer.

Personally, I prefer using browserify as it allows for using CommonJS modules in the browser, which is highly appreciated.

javascript angularjs browserify

Answer 1

Answer №1

If you're looking for a way to handle lazy loading in Browserify, you might want to consider exploring ocLazyLoad. It's a powerful tool that can load various file types like json, css, js, and templates dynamically into your running Angular application.

For an enhanced experience, pairing ocLazyLoad with a router (such as the default Angular one or ui-router) can work wonders.

You can find some helpful 'seed projects' demonstrating how to use ocLazyLoad with SystemJS:

However, there's an alternative approach available.

If you opt for ui-router, ui-router-extras, and ocLazyLoad, you can implement lazy loading of states like this:

main.js

/** 
 * Include necessary dependencies in our main module.
 */
var main = angular.module('main', [ 'ui.router', 'ct.ui.router.extras.future', 'oc.lazyLoad' ]);

/**
 * Define the lazily loaded states.
 */
main.constant('lazyLoadedStates', [
  {
    name: 'about',
    url:  '/about',
    type: 'lazy',
    src: [
      '/path/to/about.module.js',
      '/path/to/AboutController.js'
    ]
  }
]);

/**
 * Configure the behavior when encountering a futureState with the 'lazy' type. 
 * 
 * 1. Set up a deferred object.
 * 2. Resolve the promise once all files specified in futureState.src have been loaded.
 * 3. Return the promise.
 */
main.config(function ($futureStateProvider, lazyLoadedStates) {
  $futureStateProvider.stateFactory('lazy', function ($q, $ocLazyLoad, futureState) {
    var deferred = $q.defer();

    $ocLazyLoad.load(futureState.src).then(function () {
      deferred.resolve();
    });

    return deferred.promise;
  });

  lazyLoadedStates.forEach($futureStateProvider.futureState);
});

Now that we've set up the foundation, you just need to continue adding modules and code while matching actual state definitions with the placeholders in the lazyLoadedStates constant.

about.module.js

/** 
 * Define the real '/about' state within this lazily loaded file.
 */
angular.module('about', []).config(function ($stateProvider) {
  $stateProvider.state('about', {
    url: '/about',
    controller: 'AboutController',
    template: 'some_template.html'
  });
});

AboutController.js

/** 
 * Register the AboutController in a lazily loaded file. You could also do this in about.module.js,
 * but separating it showcases loading multiple files.
 */
angular.module('about').controller('AboutController', function ($state) {
  console.log('Im on a lazy loaded state!', $state.current);
});

This should give you a good overview of setting up lazy loaded states in Angular. While I haven't found a simpler method, there may be resources available on integrating ui-router (or the default Angular router) with other lazy-loading solutions.

Documentation links:

ocLazyLoad
ui-router-extras#future

Answer 2

If you're looking for a way to handle lazy loading in Browserify, you might want to consider exploring ocLazyLoad. It's a powerful tool that can load various file types like json, css, js, and templates dynamically into your running Angular application.

For an enhanced experience, pairing ocLazyLoad with a router (such as the default Angular one or ui-router) can work wonders.

You can find some helpful 'seed projects' demonstrating how to use ocLazyLoad with SystemJS:

However, there's an alternative approach available.

If you opt for ui-router, ui-router-extras, and ocLazyLoad, you can implement lazy loading of states like this:

main.js

/** 
 * Include necessary dependencies in our main module.
 */
var main = angular.module('main', [ 'ui.router', 'ct.ui.router.extras.future', 'oc.lazyLoad' ]);

/**
 * Define the lazily loaded states.
 */
main.constant('lazyLoadedStates', [
  {
    name: 'about',
    url:  '/about',
    type: 'lazy',
    src: [
      '/path/to/about.module.js',
      '/path/to/AboutController.js'
    ]
  }
]);

/**
 * Configure the behavior when encountering a futureState with the 'lazy' type. 
 * 
 * 1. Set up a deferred object.
 * 2. Resolve the promise once all files specified in futureState.src have been loaded.
 * 3. Return the promise.
 */
main.config(function ($futureStateProvider, lazyLoadedStates) {
  $futureStateProvider.stateFactory('lazy', function ($q, $ocLazyLoad, futureState) {
    var deferred = $q.defer();

    $ocLazyLoad.load(futureState.src).then(function () {
      deferred.resolve();
    });

    return deferred.promise;
  });

  lazyLoadedStates.forEach($futureStateProvider.futureState);
});

Now that we've set up the foundation, you just need to continue adding modules and code while matching actual state definitions with the placeholders in the lazyLoadedStates constant.

about.module.js

/** 
 * Define the real '/about' state within this lazily loaded file.
 */
angular.module('about', []).config(function ($stateProvider) {
  $stateProvider.state('about', {
    url: '/about',
    controller: 'AboutController',
    template: 'some_template.html'
  });
});

AboutController.js

/** 
 * Register the AboutController in a lazily loaded file. You could also do this in about.module.js,
 * but separating it showcases loading multiple files.
 */
angular.module('about').controller('AboutController', function ($state) {
  console.log('Im on a lazy loaded state!', $state.current);
});

This should give you a good overview of setting up lazy loaded states in Angular. While I haven't found a simpler method, there may be resources available on integrating ui-router (or the default Angular router) with other lazy-loading solutions.

Documentation links:

ocLazyLoad
ui-router-extras#future

Efficiently loading components in Angular using browserify with lazy loading

Answer №1

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