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   1 # D - Property descriptor factory
   2
   3 _Originally derived from [es5-ext](https://github.com/medikoo/es5-ext) package._
   4
   5 Defining properties with descriptors is very verbose:
   6
   7 ```javascript
   8 var Account = function () {};
   9 Object.defineProperties(Account.prototype, {
  10   deposit: { value: function () {
  11       /* ... */
  12     }, configurable: true, enumerable: false, writable: true },
  13   whithdraw: { value: function () {
  14       /* ... */
  15     }, configurable: true, enumerable: false, writable: true },
  16   balance: { get: function () {
  17       /* ... */
  18     }, configurable: true, enumerable: false }
  19 });
  20 ```
  21
  22 D cuts that to:
  23
  24 ```javascript
  25 var d = require('d');
  26
  27 var Account = function () {};
  28 Object.defineProperties(Account.prototype, {
  29   deposit: d(function () {
  30     /* ... */
  31   }),
  32   whithdraw: d(function () {
  33     /* ... */
  34   }),
  35   balance: d.gs(function () {
  36     /* ... */
  37   })
  38 });
  39 ```
  40
  41 By default, created descriptor follow characteristics of native ES5 properties, and defines values as:
  42
  43 ```javascript
  44 { configurable: true, enumerable: false, writable: true }
  45 ```
  46
  47 You can overwrite it by preceding _value_ argument with instruction:
  48 ```javascript
  49 d('c', value); // { configurable: true, enumerable: false, writable: false }
  50 d('ce', value); // { configurable: true, enumerable: true, writable: false }
  51 d('e', value); // { configurable: false, enumerable: true, writable: false }
  52
  53 // Same way for get/set:
  54 d.gs('e', value); // { configurable: false, enumerable: true }
  55 ```
  56
  57 ### Other utilities
  58
  59 #### autoBind(obj, props) _(d/auto-bind)_
  60
  61 Define methods which will be automatically bound to its instances
  62
  63 ```javascript
  64 var d = require('d');
  65 var autoBind = require('d/auto-bind');
  66
  67 var Foo = function () { this._count = 0; };
  68 autoBind(Foo.prototype, {
  69   increment: d(function () { ++this._count; });
  70 });
  71
  72 var foo = new Foo();
  73
  74 // Increment foo counter on each domEl click
  75 domEl.addEventListener('click', foo.increment, false);
  76 ```
  77
  78 #### lazy(obj, props) _(d/lazy)_
  79
  80 Define lazy properties, which will be resolved on first access
  81
  82 ```javascript
  83 var d = require('d');
  84 var lazy = require('d/lazy');
  85
  86 var Foo = function () {};
  87 lazy(Foo.prototype, {
  88   items: d(function () { return []; })
  89 });
  90
  91 var foo = new Foo();
  92 foo.items.push(1, 2); // foo.items array created
  93 ```
  94
  95 ## Installation
  96 ### NPM
  97
  98 In your project path:
  99
 100         $ npm install d
 101
 102 ### Browser
 103
 104 You can easily bundle _D_ for browser with [modules-webmake](https://github.com/medikoo/modules-webmake)
 105
 106 ## Tests [![Build Status](https://travis-ci.org/medikoo/d.png)](https://travis-ci.org/medikoo/d)
 107
 108         $ npm test