CODEWITHSUNDEEP
javascriptoopsetterdefineproperty
YemSalat
YemSalat

Reputation: 21526

Object create define property setter

I need to make it so that every time a specific property on my object is changed - it will call a special method on the same object.

Example:

MyObject.prototype = Object.create({
    specialMethod: function() { /* ... */ }
  }, {
    someValue: {
      set: function(value) {

        /* HOW DO I ASSIGN THE VALUE TO MyObject HERE?*/
        /* I can't do: this.someValue=value, that would create endless recursion */

        this.specialMethod();
      }
    }
  });

How do I assign the value to MyObject within the property setter?

Upvotes: 3

Views: 5321

Answers (1)

Bergi
Bergi

Reputation: 665555

There is no storage place in a getter/setter property, you cannot store values on it. You need to store it somewhere else and create a getter for that. Two solutions:

  1. Use a second, "hidden" property:

    MyObject.prototype.specialMethod: function() { /* ... */ };
Object.defineProperty(MyObject.prototype, "someValue", {
    set: function(value) {
        this._someValue = value;
        this.specialMethod();
    },
    get: function() {
        return this._someValue;
    }
});

  2. Use a closure variable (typically created on construction of the instance):

    function MyObject() {
    var value;
    Object.defineProperty(this, "someValue", {
        set: function(v) {
            value = v;
            this.specialMethod();
        },
        get: function() {
            return value;
        }
    });
}
MyObject.prototype.specialMethod: function() { /* ... */ };

Upvotes: 6

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