javascript - 如何从对象函数返回对象 - javascript？

Question

我有一个像下面这样的对象

 function obj() {

     this.cellSize = 50;

     this.createBlock = function() { // creates a block object
        this.x = 0;
        this.y = 0 - (this.cellSize * 1.5);
        this.baseVelocity = 1;
        this.velocity = this.baseVelocity;
        return this;
    };

    this.activeBlock = this.createBlock(); // active block object

    this.nextBlock = this.createBlock(); // next block object
 }

当我检查 obj.activeBlock 时，我没有得到应该从 obj.createBlock 返回的对象？

谢谢，

Answer 1

你可能想要这样的东西:

function obj() {
     var that = this;
     this.cellSize = 50;

     this.createBlock = function() { // creates a block object
        this.x = 0;
        this.y = 0 - (that.cellSize * 1.5);
        this.baseVelocity = 1;
        this.velocity = this.baseVelocity;
        return this;
    };

    this.activeBlock = new this.createBlock(); // active block object

    this.nextBlock = new this.createBlock(); // next block object
}

createBlock函数中的this应该和obj()的this不同。您还需要为每个 block 使用 new 创建一个新对象。如果 cellSize 应该是一个常量，您可以将代码重写为闭包:

function obj() {
     var cellSize = 50;

     this.createBlock = function() { // creates a block object
        this.x = 0;
        this.y = 0 - (cellSize * 1.5);
        this.baseVelocity = 1;
        this.velocity = this.baseVelocity;
        return this;
    };

    this.activeBlock = new this.createBlock(); // active block object

    this.nextBlock = new this.createBlock(); // next block object
}