toString()  Object  instance method JS Home  <<  JS Reference  <<  Object  <<  toString()

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Description

Returns a string of the specified object.

• Automatically invoked when an object is called and a string is expected or when viewing the object as a string.
• The Object.toString() method is inherited by all Object descendants.
• Unless overridden by a custom object toString() returns [object Object].

Syntax

Parameters

None.

Examples

The code below creates an object and displays it.

// Create an object.
anObject = new Object();

alert(anObject.toString() + ' anObject is an Object instance.');

Overriding The Object.toString() Method

As you can see when pressing the above button the default for toString() on an objectType of Object returns [object Object]. If you want something meaningful returned for your object, you need to override the Object.toString() method.

The code below creates a custom object type function and overrides the Object.toString() method. We then create and display a string of the object which will use our custom toString() method.

// Define a custom object type function.
function HomeOwner(firstName,lastName) {  
  this.firstName=firstName;  
  this.lastName=lastName;  
}  

// Define a custom override function for toString().
HomeOwner.prototype.toString = function HomeOwnerToString() {  
  var owns = this.firstName + ' ' + this.lastName + ' owns a house!';  
  return owns;  
}

// Create and print a HomeOwner object.
owner = new HomeOwner('Barney','Magrew');  

alert(owner.toString());

Related Tutorials

JavaScript Basic Tutorials - Lesson 7 - Objects

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