Angular Performance Optimization
Performance is very important for any web application, and Angular is no exception. There are several techniques that can be used to optimize the performance of an Angular application. In this article, we will take a look at some of the most effective ways to optimize the performance of an Angular application.
Using Lazy Loading
Lazy loading is a feature in Angular that allows you to load parts of your application only when they are needed, rather than loading everything up front. This can improve the initial loading time of your application and make it feel faster and more responsive.
In Angular, lazy loading is achieved by creating separate modules for different parts of your application, and then using the loadChildren property in the RouterModule to specify that the module should be loaded lazily, rather than being loaded immediately when the application starts up.
Using OnPush Change Detection Strategy
The OnPush change detection strategy is a technique that can be used to improve the performance of your application. By default, Angular checks all of the components in your application for changes on every change detection cycle. This can be a costly operation, specially if you have a large number of components. With the OnPush change detection strategy, Angular only checks the components that have been marked as OnPush for changes.
Default Change Detection: Angular detects the changes in the application, within the tree of components. It starts by checking the root component, then its children, then its grand-children, until all components are checked. Then all the necessary DOM updates are applied in one batch.
But this is not a very good idea to check every component on every change. And that’s often not really necessary. Whenever a change occurs, Angular starts checking all components again, starting from the root component and descending in each child component. It affect the performance.
Hence OnPush Change Detection Strategy is the best solution which updates a component’s view only when a marked input property changes or an event originates from the component. This strategy helps in improving the performance of Angular applications by reducing the number of change detection cycles. By using the OnPush strategy, the framework does not run change detection for a component unless it has to, resulting in better performance and improved scalability.
Using Detach Change Detection/NgZone
In Angular, Change Detection is the process of checking for changes in the component’s data and updating the view accordingly. By default, change detection runs for every component, but in some cases, it’s not necessary to run change detection for all components all the time. In such cases, the detach method of the ChangeDetectorRef can be used to detach the component from the change detection cycle, thus improving performance.
The NgZone is a zone.js library that is used in Angular to perform certain tasks in an asynchronous manner, such as change detection. The NgZone is automatically created by Angular and can be injected into a component’s constructor. The use of NgZone with detach allows developers to manually control the change detection process, improving application performance and fixing issues related to change detection.
In summary, the detach method of the ChangeDetectorRef and the NgZone service are used to manually control the change detection process, improving performance and fixing issues in an Angular application.
Using Ahead-of-Time (AOT) compilation
Ahead-of-Time (AOT) compilation is a technique that can be used to improve the performance of your application. AOT compilation pre-compiles your application’s templates and components, which can result in faster startup times and reduced memory usage. To enable AOT compilation, you can use the –aot flag when building your application with the Angular CLI.
Using Pure Pipes
In Angular, pipes are used to transform data before displaying it to the user. A pure pipe is a type of pipe that only executes its transformation logic when it detects a change in the input data. The Angular framework considers an input value pure if it is a primitive value (e.g. a string, number, or boolean), an object or array with its properties frozen (using Object.freeze()), or an object or array created by a pure function.
By default, Angular executes the transformation logic of pipes for every change detection cycle, even if the input data hasn’t changed. This can lead to performance issues in large applications. By using a pure pipe, Angular only executes the transformation logic if the input data changes, providing a performance optimization.
Using Trackby
“trackBy” is a feature in Angular that helps to improve performance by keeping track of the items in a list and updating only the items that have changed. This feature is used with “ngFor” directive to optimize the performance of an Angular application by reducing the number of DOM (Document Object Model) updates and preventing the creation of unnecessary DOM elements.
Using Web Workers
Web Workers is a feature of modern browsers that allows you to run JavaScript code in a separate thread, outside of the main UI thread. In Angular, web workers can be used to perform heavy-duty computations, freeing up the main UI thread and improving the overall performance of the application.
To use web workers in Angular, you need to create a separate JavaScript file for the worker and run it in a worker thread. Angular provides a utility library called @angular/platform-webworker that makes it easier to use web workers in Angular applications.
Using Preloading Modules
Preloading modules in Angular is a performance optimization technique that allows you to load parts of your application in advance, so they’re available instantly when needed. This can greatly improve the user experience and reduce the time required to load a page.
You can preload modules using the “preloadingStrategy” property of the “RouterModule” when setting up your application’s routing. Angular provides two preloading strategies: “PreloadAllModules” and “NoPreloading”.
Using Resolve Guards
Resolve guards in Angular are a performance optimization technique that allow you to pre-fetch data required by a component before navigating to that component. Resolve guards are used to load data before the component is activated, so that the data is available immediately when the component is displayed.
Unsubscribe from Observables
In Angular, it’s important to unsubscribe from observables when they’re no longer needed to avoid memory leaks. This is because observables can continue to emit values even after a component is destroyed, causing the component to persist in memory.
So these are the Angular performance techniques.
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