Why does console.log() output [object Object] in JavaScript?

Question

console.log(({
  title: "The Three Musketeers",
  author: "Alexandre Dumas",
  price: "$49"
}).toString());

It outputs an Object as [object Object], even though I am calling .toString() on it. Can anyone please explain why this happens?

What did you expect it to print and why did you expect that? — takendarkk
– takendarkk, Commented Sep 4, 2017 at 23:53
Your object does not have its own toString, so it uses the one from object. — Paul Rooney
– Paul Rooney, Commented Sep 4, 2017 at 23:57
Because that's what ECMA-262 says it should return. What did you expect? — RobG
– RobG, Commented Sep 5, 2017 at 0:02

Obsidian Age · Accepted Answer · 2017-09-04 23:53:28Z

1

Because for have built a JavaScript object that you are attempt to convert to a string. You are attempting to convert the entire object to a string, which can't (really) be done. As such, you simply get text that says "Hey, we've got an object here".

If however, you were to run .toString() on a property of that object (which is probably your intent), you would get a string representation of that property. This can be done by accessing the proeprty with the dot notation just before calling .toString(), as follows:

console.log(({
  title: "The Three Musketeers",
  author: "Alexandre Dumas",
  price: "$49"
}).title.toString());

answered Sep 4, 2017 at 23:53

Obsidian Age

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Comments

Djaouad · Accepted Answer · 2017-09-04 23:53:41Z

1

That's what happens when you try to convert or add an object to a string (which also tries to convert it to a string), what you're looking for is JSON.stringify(object) :

console.log(
    JSON.stringify(
        {title : "The Three Musketeers", author: "Alexandre Dumas", price: "$49"}
    )
);

answered Sep 4, 2017 at 23:53

Djaouad

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Comments

Nick · Accepted Answer · 2017-09-04 23:53:30Z

0

If you're looking for a JSON string representation of the object, look into JSON.stringify()

answered Sep 4, 2017 at 23:53

Nick

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Comments

Mikkel · Accepted Answer · 2017-09-04 23:54:04Z

0

If you do it this way it will work better

let object = {
  title: "The Three Musketeers",
  author: "Alexandre Dumas",
  price: "$49"
}
console.log("My object",object);

It's because it doesn't know how to render your object

answered Sep 4, 2017 at 23:54

Mikkel

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Comments

ledicjp · Accepted Answer · 2017-09-04 23:55:25Z

0

The method you're looking for is JSON.stringify(). Try this:

JSON.stringify({
  title: "The Three Musketeers",
  author: "Alexandre Dumas",
  price: "$49"
}, null, 2);

answered Sep 4, 2017 at 23:55

ledicjp

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