Detect when input value changed in directive

Question

I\'m trying to detect when the value of an input changed in a directive. I have the following directive:

Answer 1

You need to make an input property of input and then use the ngOnChanges hook to tell when the input property changes.

@Directive({
    selector: '[number]'
})
export class NumberDirective implements OnChanges {
    @Input() public number: any;
    @Input() public input: any;

    ngOnChanges(changes: SimpleChanges){
      if(changes.input){
        console.log('input changed');
      }
    }
}

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