Object.prototype.toSource()

オブジェクトのソースコードを表す文字列を返します。

構文

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

戻り値

オブジェクトのソースコードを表す文字列

説明

toSource メソッドは以下の値を返します。

• 組み込みの Boolean オブジェクトに対しては、toSource はソースコードが利用不可能なことを示す以下の文字列を返します。

function Boolean() {
   [native code]
}

• Boolean のインスタンスに対しては、toSource はソースコードを表す文字列を返します。

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.

例

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"})

仕様

Not part of any standard. Implemented in JavaScript 1.3.

ブラウザ実装状況

参照

• Object.prototype.toString()