Everything you need to know about the ExpressionChangedAfterItHasBeenCheckedError error

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• During change detection, Angular performs checks for each component:
  • Update bound properties for all child components/directives.
  • Call ngOnInit, ngOnChanges and ngDoCheck lifecycle hooks on all child components/directives.
  • Update DOM for the current component.
  • Run CD for the child component.
  • Run ngAfterViewInit lifecycle hook for all child components/directives.
• After each operation, Angular remembers what values it used to perform an operation. They are stores in the oldValues property of the component view. After the checks have been done, Angular starts the next digest cycle.
• Causes of value change:
  • Almost always, it’s the child component, wh

Filter out nulls in array

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