Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
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.SIMD.%type%.prototype.toSource()
—SIMD
objects.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. Implemented in JavaScript 1.3.
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | No support | (Yes) | ? | ? | ? |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | ? | ? | (Yes) | ? | ? | ? |