Why console.log(obj) show structure of obj instead of return value of toString()

Question

I have an object with the following structure

var obj = {
    toString: function(){ return "20" },
    valueOf: function(){  return 10; }
};

alert(obj) //20
console.log(obj) //Object {toString: function, valueOf: function}

unlike alert(obj) why console.log(obj) shows object structure instead of return value of toString()??

In both scenario expecting string text.

possible duplicate of [alert() return different from console.log()?](http://stackoverflow.com/questions/3909006/alert-return-different-from-console-log) — Gilles 'SO- stop being evil', Mar 13 '14 at 21:14

score 2 · Accepted Answer · answered Mar 12 '14 at 10:35

2

It is only for the good of debugging.
Would like to to see obj.toString() in console? Use:

Console.count(obj); //also will show how many times obj has been invoked

Usefull links:

answered Mar 12 '14 at 10:35

Ruslan Ismagilov

1,360
7
14

score 1 · Answer 2 · answered Mar 12 '14 at 10:08

1

console.log intended for debugging, and alert intended for showing text, so alert seek toString function if it exists then show it result, instead it will show [Object object].

answered Mar 12 '14 at 10:08

Sergey92zp

589
4
22

That I agree but why console.log() does not call toString() – Alex Mathew Mar 12 '14 at 10:12
3

Because it's more useful for debugging to have the full object structure. – Scimonster Mar 12 '14 at 10:12
console.log(new String("hello")); //String {0: "h", 1: "e", 2: "l", 3: "l", 4: "o", length: 5} console.log(String("hello")); //hello – Alex Mathew Mar 12 '14 at 10:21

score 1 · Answer 3 · answered Oct 09 '15 at 04:37

1

If you want to get text in console then just add empty string like bellow

console.log(obj + "");

answered Oct 09 '15 at 04:37

Mitul

3,431
2
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score 0 · Answer 4 · edited May 23 '17 at 10:29

In the words of Tim Down, the method

alert() converts the object passed to it into a string using the object's toString() method [whereas] console.log() is not only used to display a simple string but it can also allow you to interact with the object passed to it.

Also console.log() is used for debugging. In the words of Jan Hančič,

You can for instance log something to the console when something happens.

You use console.log to view full object structure.

Why console.log(obj) show structure of obj instead of return value of toString()

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