js-class
v0.0.3
Published
Define classes in Javascript
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Define Classes in Javascript
This is a simple module providing a simple Class
function to simplify class definition in Javascript.
Install
For Node.js
npm install js-class
For browser, use bower
bower install js-class
To rebuild js-class.min.js
, type:
npm install
npm run-script build
How to Use
With Node.js:
var Class = require('js-class');
In browser, just include js-class.min.js
Prototype
Class(baseClass, prototype, options);
Parameters
baseClass
: baseClass type, optional, default is Object;prototype
: the prototype for new class;options
: other options like implements and statics, see details below.
Returns
The newly defined class.
Details
A simple and quick sample:
var Class = require('js-class');
var MyClass = Class({
constructor: function (value) {
// this is the constructor
this._value = value;
},
print: function () {
console.log(this._value);
},
// getter/setter is supported
get value () {
return this._value;
},
set value (value) {
if (!isFinite(value)) {
throw new Error('Bad Value');
}
this._value = value;
}
});
var myObject = new MyClass(1);
myObject.print(); // get 1
myObject.value = myObject.value + 100;
myObject.print(); // get 101
A simple inheritance sample:
var BaseClass = Class({
constructor: function (value) {
this.value = value;
},
print: function () {
console.log('BaseClass: %d', this.value);
}
});
var SubClass = Class(BaseClass, {
constructor: function (val1, val2) {
BaseClass.prototype.constructor.call(this, val1 + val2);
},
print: function () {
console.log('SubClass');
BaseClass.prototype.print.call(this);
}
});
var myObject = new SubClass(1, 2);
myObject instanceof SubClass; // true
myObject instanceof BaseClass; // true
myObject.print();
// get
// SubClass
// BaseClass: 3
Multiple inheritance with implements
var ActiveBuffer = Class(Buffer, {
// override Clearable
clear: function () {
// TODO I hate to be cleared
this.emit('cleared');
}
}, {
implements: [EventEmitter, Clearable]
});
var buffer = new ActiveBuffer().on('cleared', function () { console.log('CLEARED'); });
buffer.clear();
buffer instanceof Buffer; // true
buffer instanceof EventEmitter; // false
buffer instanceof Clearable; // false
Static members
var Singleton = Class({
constructor: function () {
// ...
},
work: function () {
// ...
}
}, {
statics: {
get instance () {
if (!Singleton._instance) {
Singleton._instance = new Singleton();
}
return Singleton._instance;
}
}
});
Singleton.instance.work();
Type Information
The keyword instanceof
can be used to check the type inherited directly. But it doesn't work with implemented
types.
Use Class.is
for all the cases:
Class.is(object).typeOf(Type)
We also have two aliases:
Class.is(object).a(Type)
Class.is(object).an(Object)
License
MIT/X11 License