PropertyPatch

This is basically just a slightly smoother way to add getters/setters to a JS class. It's a thin wrapper over the top of Object.defineProperty that just makes a little more sense to my brain.

Forms

It's available in two forms.

function form

One form is just a function that you require and then .call in your constructor:

var add_property = require('property_patch').add_property;

function Foo() {
  add_property.call(this, 'bar');
}

var f = new Foo();
f.bar = 5;
f.bar; // === 5

Object patch form

You can also patch it into Object.prototype if you're feeling dirty. I prefer this form, but I know it's frowned upon, so that's why you have options.

require('property_patch').patch();

function Foo() {
  this.add_property('bar');
}

var f = new Foo();
f.bar = 5;
f.bar; // === 5

BUT WHY?!

Why would I want this? Well, if you're writing OO code, then everything should really be a method call, never a direct property access. However, it is super lame to have to define and call explicit get_foo and set_foo methods on every class. Using properties defined this way allows you to have real getters and setters without the fuss.

Contrived example time!

Class definition using add_property

function Foo() {
  this.add_property('bar', 1);
}

Foo.prototype.get_bar = function() {
  return this._bar + 5;
}

Foo.prototype.set_bar = function(val) {
  if (typeof(val) !== 'number') throw "ONLY NUMBERS PLZ";
  this._bar = val;
}

Using the property

So notice the custom get_bar and set_bar methods. Because we defined the property 'bar' in the constructor, we can say stuff like this:

var f = new Foo();
f.bar = 5;
f.bar; // === 10 (whoa!)
f.bar = "hey"; // not allowed! throws an error!

Default values

Also, you can set an optional default value for a property you defined this way. In Foo up there, we set the default for bar to 1.

var foo = new Foo();
f.bar; // === 1

Pretty neat, huh? Oh... Well, I thought it was cool. Don't be so negative all the time.