105 lines
2.7 KiB
Markdown
105 lines
2.7 KiB
Markdown
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# D
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## Property descriptor factory
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_Originally derived from [es5-ext](https://github.com/medikoo/es5-ext) package._
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Defining properties with descriptors is very verbose:
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```javascript
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var Account = function () {};
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Object.defineProperties(Account.prototype, {
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deposit: { value: function () {
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/* ... */
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}, configurable: true, enumerable: false, writable: true },
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withdraw: { value: function () {
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/* ... */
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}, configurable: true, enumerable: false, writable: true },
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balance: { get: function () {
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/* ... */
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}, configurable: true, enumerable: false }
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});
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```
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D cuts that to:
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```javascript
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var d = require('d');
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var Account = function () {};
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Object.defineProperties(Account.prototype, {
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deposit: d(function () {
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/* ... */
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}),
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withdraw: d(function () {
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/* ... */
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}),
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balance: d.gs(function () {
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/* ... */
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})
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});
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```
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By default, created descriptor follow characteristics of native ES5 properties, and defines values as:
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```javascript
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{ configurable: true, enumerable: false, writable: true }
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```
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You can overwrite it by preceding _value_ argument with instruction:
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```javascript
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d('c', value); // { configurable: true, enumerable: false, writable: false }
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d('ce', value); // { configurable: true, enumerable: true, writable: false }
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d('e', value); // { configurable: false, enumerable: true, writable: false }
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// Same way for get/set:
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d.gs('e', value); // { configurable: false, enumerable: true }
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```
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### Installation
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$ npm install d
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To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: [Browserify](http://browserify.org/), [Webmake](https://github.com/medikoo/modules-webmake) or [Webpack](http://webpack.github.io/)
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### Other utilities
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#### autoBind(obj, props) _(d/auto-bind)_
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Define methods which will be automatically bound to its instances
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```javascript
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var d = require('d');
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var autoBind = require('d/auto-bind');
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var Foo = function () { this._count = 0; };
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Object.defineProperties(Foo.prototype, autoBind({
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increment: d(function () { ++this._count; });
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}));
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var foo = new Foo();
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// Increment foo counter on each domEl click
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domEl.addEventListener('click', foo.increment, false);
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```
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#### lazy(obj, props) _(d/lazy)_
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Define lazy properties, which will be resolved on first access
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```javascript
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var d = require('d');
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var lazy = require('d/lazy');
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var Foo = function () {};
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Object.defineProperties(Foo.prototype, lazy({
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items: d(function () { return []; })
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}));
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var foo = new Foo();
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foo.items.push(1, 2); // foo.items array created and defined directly on foo
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```
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## Tests [](https://travis-ci.org/medikoo/d)
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$ npm test
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