为什么不在javascript中调用覆盖toString()

Question

我试图覆盖toString()但我发现,被覆盖的函数根本没有被调用.

我已经完成了这个和这个,但我无法追踪我的错误.

我的尝试:

DIRECTION = {
    NONE : 0,
    DIAGONAL: 1,
    UP: 2,
    LEFT: 3
};

var Node  = function () {
    this.direction =  DIRECTION.NONE;
    this.weight = 0;
};
Node.prototype.toString = function NodeToSting(){
    console.log('Is called');
    var ret = "this.weight";
    return ret;
};

(function driver(){
    var node1 = new Node();
    console.log(node1);
    //findLcs("ABCBDAB", "BDCABA");
})();

输出:

{ direction: 0, weight: 0 }

Answer 1

console.log将文字值输出到控制台 - 它不会将您的对象强制转换为字符串,因此不会执行您的toString实现.

您可以强制它输出如下字符串:

console.log(""+node1);

例:

DIRECTION = {
    NONE : 0,
    DIAGONAL: 1,
    UP: 2,
    LEFT: 3
};

var Node  = function () {
    this.direction =  DIRECTION.NONE;
    this.weight = 0;
};
Node.prototype.toString = function NodeToSting(){
    console.log('Is called');
    var ret = "this.weight";
    return ret;
};

(function driver(){
    var node1 = new Node();
    alert(""+node1);
    //findLcs("ABCBDAB", "BDCABA");
})();