Web/JavaScript/Reference/Global objects/Object/toSource

ObsoleteThis feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

The toSource() method returns a string representing the source code of the object.

Syntax

Object.toSource();
obj.toSource();

Return value

A string representing the source code of the object.

Description

The toSource() method returns the following values:

• For the built-in Object object, toSource() returns the following string indicating that the source code is not available:

  function Object() {
      [native code]
  }

• For instances of Object, toSource() returns a string representing the source code.

You can call toSource() while debugging to examine the contents of an object.

Overriding the toSource() method

It is safe for objects to override the toSource() method. For example:

function Person(name) {
  this.name = name;
}

Person.prototype.toSource = function Person_toSource() {
  return 'new Person(' + uneval(this.name) + ')';
};

console.log(new Person('Joe').toSource()); // ---> new Person("Joe")

Built-in toSource() methods

Each core JavaScript type has its own toSource() method. These objects are:

• Array.prototype.toSource()  — Array object.
• Boolean.prototype.toSource()  — Boolean object.
• Date.prototype.toSource()  — Date object.
• Function.prototype.toSource()  — Function object.
• Number.prototype.toSource()  — Number object.
• RegExp.prototype.toSource()  — RegExp object.
• String.prototype.toSource()  — String object.
• Symbol.prototype.toSource()  — Symbol object.
• Math.toSource() — Returns the String "Math".

Limitations on cyclical objects

In the case of objects that contain references to themselves, e.g. a cyclically linked list or a tree that can be traversed both ways, toSource() will not recreate the self-reference, as of Firefox 24. For example:

var obj1 = {};
var obj2 = { a: obj1 };
obj1.b = obj2;

console.log('Cyclical: ' + (obj1.b.a == obj1));

var objSource = obj1.toSource(); // returns "({b:{a:{}}})"

obj1 = eval(objSource);

console.log('Cyclical: ' + (obj1.b.a == obj1));

If a cyclical structure is employed and toSource() is needed, the object must provide an override to toSource(), either using a reference to a constructor or providing an anonymous function.

Examples

Using toSource()

The following code defines the Dog object type and creates theDog, an object of type Dog:

function Dog(name, breed, color, sex) {
  this.name = name;
  this.breed = breed;
  this.color = color;
  this.sex = sex;
}

theDog = new Dog('Gabby', 'Lab', 'chocolate', 'female');

Calling the toSource() method of theDog displays the JavaScript source that defines the object:

theDog.toSource();
// returns ({name:"Gabby", breed:"Lab", color:"chocolate", sex:"female"})

Specifications

Not part of any standard.

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
toSource Deprecated'Non-standard'	Chrome No support No	Edge No support No	Firefox No support 1 — 74 Notes' No support 1 — 74 Notes' Notes' Starting in Firefox 74, toSource() is no longer available for use by web content. It is still allowed for internal and privileged code.	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android No support No	Firefox Android Full support 4	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support No	nodejs No support No

Legend

Full support  

Full support

No support  

No support

Non-standard. Expect poor cross-browser support.'

Non-standard. Expect poor cross-browser support.

Deprecated. Not for use in new websites.'

Deprecated. Not for use in new websites.

See implementation notes.'

See implementation notes.

See also

• Object.prototype.toString()

Object.prototype.toSource() by Mozilla Contributors is licensed under CC-BY-SA 2.5.