How to detect attribute change in angular 2?

Question

Given the following code:

Parent component:

<my-cmp readonly></my-cmp>

Child component:

...
constructor(@Attribute('readonly') readonly) {
    this._readonly = readonly !== null ? 1 : 0;
  }
...

How do I detect changes to the readonly attribute?

Answer 1

@Input()
set readonly(val) {
 if(val === '') {
  console.log('set');
 } else {
  console.log('removed'); 
}