d

Property descriptor factory

D - Property descriptor factory

Originally derived from es5-ext package.

Defining properties with descriptors is very verbose:

var Account = function () {};
Object.defineProperties(Account.prototype, {
  deposit: { valuefunction () {
      /* ... */
    }, configurable: true, enumerable: false, writable: true },
  whithdraw: { valuefunction () {
      /* ... */
    }, configurable: true, enumerable: false, writable: true },
  balance: { getfunction () {
      /* ... */
    }, configurable: true, enumerable: false }
});

D cuts that to:

var d = require('d');
 
var Account = function () {};
Object.defineProperties(Account.prototype, {
  deposit: d(function () {
    /* ... */
  }),
  whithdraw: d(function () {
    /* ... */
  }),
  balance: d.gs(function () {
    /* ... */
  })
});

By default, created descriptor follow characteristics of native ES5 properties, and defines values as:

{ configurable: true, enumerable: false, writable: true }

You can overwrite it by preceding value argument with instruction:

d('c', value); // { configurable: true, enumerable: false, writable: false } 
d('ce', value); // { configurable: true, enumerable: true, writable: false } 
d('e', value); // { configurable: false, enumerable: true, writable: false } 
 
// Same way for get/set: 
d.gs('e', value); // { configurable: false, enumerable: true } 

Define methods which will be automatically bound to its instances

var d = require('d');
var autoBind = require('d/auto-bind');
 
var Foo = function () { this._count = 0; };
autoBind(Foo.prototype, {
  increment: d(function () { ++this._count; });
});
 
var foo = new Foo();
 
// Increment foo counter on each domEl click 
domEl.addEventListener('click', foo.increment, false);

Define lazy properties, which will be resolved on first access

var d = require('d');
var lazy = require('d/lazy');
 
var Foo = function () {};
lazy(Foo.prototype, {
  items: d(function () { return []; })
});
 
var foo = new Foo();
foo.items.push(1, 2); // foo.items array created 

In your project path:

$ npm install d

You can easily bundle D for browser with modules-webmake

Tests

$ npm test