What are some ways to improve the performance of an AngularJS application?

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ICSM Computer · Answer

Improving the performance of an AngularJS application involves optimizing various aspects such as data binding, digest cycle efficiency, lazy loading, and reducing unnecessary computations. Here are some key strategies:
1. Optimize Digest Cycle
Use ng-if instead of ng-show/ng-hide
ng-if removes the element from the DOM, while ng-show just hides it, reducing the number of watchers.
Minimize ng-repeat usage
Use one-time binding (::) for static data.Use track by to improve performance:
andlt;div ng-repeat="item in items track by item.id"andgt;
Consider pagination or infinite scrolling to reduce large lists.
and 
2. Reduce Watchers and Bindings
Use one-time binding (::) for data that doesn’t change:Remove unnecessary $watch expressions.
andlt;h1andgt;{{ ::title }}andlt;/h1andgt;Use debouncing or throttling for events like keyup 
or scroll using lodash or $timeout.
and 
3. Lazy Loading and Minification
Lazy load Angular modules using ocLazyLoad or 
ui-router’s resolve.Minify and concatenate JavaScript and CSS files to reduce HTTP requests.
and 
4. Optimize Filters and Expressions
Avoid using filters inside ng-repeat as they create a new function call in each digest cycle:
andlt;div ng-repeat="user in users | filter:searchText"andgt;
Instead, use pre-filtering in the controller:
$scope.filteredUsers = $filter('filter')($scope.users, $scope.searchText);Use limitTo instead of filter inside ng-repeat where possible.
and 
5. Optimize API Calls
Use $cacheFactory or localStorage to store API responses.Debounce API calls when typing in a search input.Use resolve in ui-router to fetch data before rendering a view.
6. Use bindOnce for Directives
In custom directives, avoid scope: {} for static data.Use bindToController: true for better performance.
7. Avoid Deep Watches
$scope.$watch with deep watching (true as the third argument) slows down performance. Avoid it if possible:
$scope.$watch('largeObject', function(newVal, oldVal) {
    // Avoid deep watch if not necessary
}, true);
8. Optimize DOM Manipulations
Use directives instead of controllers to manipulate the DOM.
Use $timeout or $applyAsync to batch updates and reduce digest cycles.
9. Reduce Dependencies
Remove unnecessary third-party libraries.
Use AngularJS' built-in services instead of external ones if possible.
10. Enable Production Mode
Use ng-strict-di to catch dependency injection issues in production.
Minify and use AngularJS in production mode (angular.min.js).

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What are some ways to improve the performance of an AngularJS application?

ICSM Computer

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1 Answers

1. Optimize Digest Cycle

2. Reduce Watchers & Bindings

3. Lazy Loading & Minification

4. Optimize Filters & Expressions

5. Optimize API Calls

6. Use `bindOnce` for Directives

7. Avoid Deep Watches

8. Optimize DOM Manipulations

9. Reduce Dependencies

10. Enable Production Mode

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