Properties

Class properties#

A class declaration can have default values set, if no other values are set at instantiation they will stay as they are.

import $Class from "@Class";

/**
 * @property {string} type - the type of the Class
 */
var MyClass = $Class.declare("MyClass", {
    properties: {
        type: "MyClass"
    }
});

// A class that inherits from a superclass can refine its properties.
/**
 * @extends MyClass
 * @inheritdoc
 */
var MyChildClass = $MyClass.declare("MyChildClass", {
    properties: {
        type: "MyChildClass"
    }
});

var myClass = new MyClass();
console.log(myClass.type); // MyClass

// At instantiation it's also possible to override the properties values
var myOtherClass = new $MyClass({ type: "MyCoolClass" });
console.log(myOtherClass.type); // MyCoolClass

var myChildClass = new MyChildClass();
console.log(myChildClass.type); // MyChildClass

The constructor has access to the resolved properties, and can override their values.

Data type#

Primitives#

The type of property can be any of the primitives supported by javascript:

• undefined
• null
• boolean
• number
• string

Object#

Binding#

The property value can be a function, named a binding function. A binding function let you compute the value of the property with a function, based on other properties values. Dynamic properties can be declared as functions or as arrow expressions:

• myProp: function () { return this.myOtherProp; }
• myProp: ({myOtherProp}) => { return myOtherProp}
• myProp: ({myOtherProp}) => myOtherProp

All declarations above result to ‘myProp’ having the same value as ‘myOtherProp’. When ‘myOtherProp’ change, ‘myProp’ will automatically be updated when we will try to get its value.

Properties options#

To define a property option, you must define the property by using its class. The following properties (exclusive) are supported:

var MyClass = $Class.declare("MyClass", {
    properties: {
     myProp: $Property("myProp", {readonly: true})
    }
});
var myClass = new MyClass();
myclass.myProp = "anotherValue"; // will raise an error