How do I fix Expressionchangedafterithasbeencheckederror in Angular?

ExpressionChangedAfterItHasBeenCheckedError occurs in Angular when a binding’s value is updated after the change detection process has run and checked it. This usually happens when you update a value asynchronously or indirectly within the same change detection cycle. To fix this error, you can use one of the following methods:

1. Use setTimeout:

Wrap the code that updates the value in a setTimeout function. This will run the code in the next event loop cycle, allowing Angular’s change detection to complete before updating the value.

Typescript

constructor(private cdRef: ChangeDetectorRef) { }

ngAfterViewInit() {
  setTimeout(() => {
    this.myValue = 'Updated value';
    this.cdRef.detectChanges();
  }, 0);
}

2. Use Promise.resolve():

Similar to setTimeout, you can use Promise.resolve() to schedule the code to run in the next event loop cycle.

Typsescript

constructor(private cdRef: ChangeDetectorRef) { }

ngAfterViewInit() {
  Promise.resolve().then(() => {
    this.myValue = 'Updated value';
    this.cdRef.detectChanges();
  });
}

3. Use ngAfterContentChecked or ngAfterViewChecked:

Move the code that updates the value to the ngAfterContentChecked or ngAfterViewChecked lifecycle hook. These hooks are called after Angular has completed checking the content or view, respectively.

Typescript

AfterViewChecked() {
  this.myValue = 'Updated value';
}

4. Use ChangeDetectorRef.detectChanges():

Manually trigger change detection for the component by calling detectChanges() on the ChangeDetectorRef instance. This is useful when you know that a value has been updated outside of Angular’s change detection mechanism.

Typescript

constructor(private cdRef: ChangeDetectorRef) { }

updateValue() {
  this.myValue = 'Updated value';
  this.cdRef.detectChanges();
}

5. Use ChangeDetectorRef.detach() and reattach() (use with caution):

Detach the component from Angular’s change detection mechanism using detach(). Update the value and then reattach the component using reattach(). Be cautious with this approach, as it can lead to unintended consequences if not used properly.

Typescript

constructor(private cdRef: ChangeDetectorRef) { }

updateValue() {
  this.cdRef.detach();
  this.myValue = 'Updated value';
  this.cdRef.detectChanges();
  this.cdRef.reattach();
}

Choose the method that best fits your use case. Keep in mind that it’s important to understand the underlying issue and ensure that your change detection strategy is optimized for your application’s needs.