「類」常量和構造函數：如何實現？

Question

我想有這樣的事情在javasript實現請：

var hat = new Hat(Hat.Color.RED, Hat.Size.MEDIUM); 

我怎麼能做到這一點，請（想招惹功能prototype但有一點成功）？

Answer 1

Hat將是一個構造函數：

function Hat(color, size) { 
    this.id = "X"+color+size; // or anything else 
} 

在原型上是「m編制方法」爲Hat實例：

Hat.prototype.raise = function() { 
    ... 
}; 

但常數是函數對象的屬性：

Hat.Color = { 
    RED: "F00", 
    GREEN: "0F0", 
    ... 
}; 
Hat.Size = { 
    MEDIUM: 0, 
    LARGE: 1, 
    ... 
}; 

如果你的庫實現了‘正確的擴展’功能（沒有什麼特別的構造函數），這也應該工作：

Object.extend(Hat, { 
    Color: {RED: "F00", GREEN: "0F0", ...}, 
    Size: = {MEDIUM: 0, LARGE: 1, ...}, 
}); 

Answer 2

你可以做，如果你創建一個Hat構造函數是這樣的：

function Hat(color, size) { 
    this.color = color; 
    this.size = size; 
} 
Hat.Color = { 
    RED: "#F00", 
    GREEN: "#0F0", 
    BLUE: "#00F" 
}; 
Hat.Size = { 
    SMALL: 0, 
    MEDIUM: 1, 
    LARGE: 2 
} 

然後，您可以創建一個new Hat，並得到其屬性

var hat = new Hat(Hat.Color.RED, Hat.Size.MEDIUM); 
var hatColor = hat.color; // "#F00" 

Answer 3

這是功能的繼承方式。它區分私有和公共方法和變量。

var Hat = function (color, size) { 
    var that = {}; 
    that.Color = { RED: 'abc'}; // object containing all colors 
    that.Size = { Medium: 'big'}; // object containing all sizes 
    that.print = function() { 
    //I am a public method 
    }; 
    // private methods can be defined here. 
    // public methods can be appended to that. 
    return that; // will return that i.e. all public methods and variables 
}