Convert objects to string in JavaScript

Published July 21, 2020

To convert an object to string in JavaScript you need to overwrite the default toString() method in any object.

All the objects in JavaScript have a default toString() method defined.

But that doesn't do any good for us.

Let's say we have an object John with name and age properties.

const John = {
  name: "John Doe",
  age: 23,
};

alert(John); // [object Object] 😟 Not good.

Because when we try to alert(John) it will show [object Object]. That's not useful for anything. But what if don't want to return [object Object] but return just the name property instead.

Well we can do that by overwriting the toString() method and returning the name property in the John object like this,

const John = {
  name: "John Doe",
  age: 23,
  toString: function () {
    return this.name;
  },
};

// only name property is returned
alert(John); // John Doe

// If we try to call the default toString() method
// console.log(John) will return ==> [object Object] which is not useful at all
// Since we have overwrote the default toString() method it will return ==> John Doe
console.log(John.toString()); // John Doe

In the alert() method ,if you try to execute the code it will show John Doe. Yes, JavaScript internally calls the toString() method when alert() is called.

In the second case if we didn't overwrite the default toString() method in The John object it will return [object Object] which is not useful at all, Now we have a useful toString() method which returns the name property.

Now, Try executing console.log(John.toString()) without defining a toString() method in John object and observe the result like this.

// No toString() method defined
const John = {
  name: "John Doe",
  age: 23,
};

console.log(John.toString()); // [object Object]   ,😟 Not useful

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