Why overriden toString() is not called in javascript

Question

I tried to override the toString() but i found that, overridden function in not getting called at all.

I have gone through this and this, but i am not able to track my mistake.

My attempt:

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");
})();

Output:

{ direction: 0, weight: 0 }

Where should it be called? `console.log` won't. – elclanrs Jul 02 '15 at 07:38 — elclanrs, Jul 02 '15 at 07:38
Where is the call to toString? – Jonathan Jul 02 '15 at 07:38 — Jonathan, Jul 02 '15 at 07:38

score 7 · Accepted Answer · answered Jul 02 '15 at 07:38

console.log outputs the literal value to the console - it will not coerce your object to a string and therefore won't execute your toString implementation.

You can force it to output a string like this:

console.log(""+node1);

Example:

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");
})();

@SunilD. That's true, but I didn't want to put a `console.log` in the SO Snippet because it's not obvious — CodingIntrigue, Jul 02 '15 at 07:51

Why overriden toString() is not called in javascript

1 Answers1