[javascript] Angular and debounce

I solved this by writing a debounce decorator. The problem described could be solved by applying the @debounceAccessor to the property's set accessor.

I've also supplied an additional debounce decorator for methods, which can be useful for other occasions.

This makes it very easy to debounce a property or a method. The parameter is the number of milliseconds the debounce should last, 100 ms in the example below.

@debounceAccessor(100)
set myProperty(value) {
  this._myProperty = value;
}


@debounceMethod(100)
myMethod (a, b, c) {
  let d = a + b + c;
  return d;
}

And here's the code for the decorators:

function debounceMethod(ms: number, applyAfterDebounceDelay = false) {

  let timeoutId;

  return function (target: Object, propName: string, descriptor: TypedPropertyDescriptor<any>) {
    let originalMethod = descriptor.value;
    descriptor.value = function (...args: any[]) {
      if (timeoutId) return;
      timeoutId = window.setTimeout(() => {
        if (applyAfterDebounceDelay) {
          originalMethod.apply(this, args);
        }
        timeoutId = null;
      }, ms);

      if (!applyAfterDebounceDelay) {
        return originalMethod.apply(this, args);
      }
    }
  }
}

function debounceAccessor (ms: number) {

  let timeoutId;

  return function (target: Object, propName: string, descriptor: TypedPropertyDescriptor<any>) {
    let originalSetter = descriptor.set;
    descriptor.set = function (...args: any[]) {
      if (timeoutId) return;
      timeoutId = window.setTimeout(() => {
        timeoutId = null;
      }, ms);
      return originalSetter.apply(this, args);
    }
  }
}

I added an additional parameter for the method decorator which let's you trigger the method AFTER the debounce delay. I did that so I could for instance use it when coupled with mouseover or resize events, where I wanted the capturing to occur at the end of the event stream. In this case however, the method won't return a value.