Angular components go through a series of lifecycle phases from creation to destruction. Each phase provides developers with the opportunity to perform specific actions. Angular provides a set of lifecycle hooks that allow you to tap into these phases. Here are the main Angular lifecycle hooks along with their typical use cases:
ngOnChanges
Usage
This hook is called when an input property of the component changes.
Example
ngOnChanges(changes: SimpleChanges) {
// React to input property changes
if (changes.myInputProperty) {
console.log('Input property changed:', changes.myInputProperty.currentValue);
}
}
ngOnInit
Usage
This hook is called once, after the component is initialized.
Example
ngOnInit() {
// Initialization logic goes here
}
ngDoCheck
Usage
This hook is called during every change detection cycle.
Example
ngDoCheck() {
// Custom change detection logic
}
ngAfterContentInit
Usage
This hook is called after the content (projected content) has been initialized.
Example
ngAfterContentInit() {
// React to content initialization
}
ngAfterContentChecked
Usage
This hook is called after the content has been checked.
Example
ngAfterContentChecked() {
// React to content changes
}
ngAfterViewInit
Usage
This hook is called after the component's view has been initialized.
Example
ngAfterViewInit() {
// React to view initialization
}
ngAfterViewChecked
Usage
This hook is called after the component's view has been checked.
Example
ngAfterViewChecked() {
// React to view changes
}
ngOnDestroy
Usage
This hook is called just before the component is destroyed.
Example
ngOnDestroy() {
// Cleanup logic goes here
}
These lifecycle hooks allow you to execute code at specific points in the component's lifecycle. Understanding and using these hooks appropriately can help manage state, perform initialization logic, and handle cleanup tasks in your Angular applications.
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