Object.prototype.toSource()

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

A string representing the source code of the object.

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.

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")

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".

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.

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"})

Not part of any standard.

• Object.prototype.toString()