Function Object Instance Properties

This section provides a tutorial example on how to use an instance properties of a function to share values across multiple function calls.

As an object, a function can also have its own instance properties. An instance property of a function can also be viewed as a static variable whose value persists across multiple function calls.

The tutorial example below shows you how to use an instance property of a function to share values across multiple function calls.

// Function_Own_Properties.js
// Copyright (c) 2013 by Dr. Herong Yang, herongyang.com

   var sign = new Function("name",
      "this.signature = name;"
      + "sign.count++;"
   )
   sign.count = 0;

// Executing it on the current object
   sign("Herong");

// Applying it on another object
   var java = new Object();
   sign.apply(java, new Array("Sun"));

// Calling it on another object
   var pc = new Object();
   sign.call(pc, "IBM");

// # of times the function has been called
   println("Call counts: " + sign.count);

Run this JavaScript file with "jrunscript" in a command window, you will get:

Call counts: 3

Table of Contents

 About This Book

 Introduction to JavaScript

 ECMAScript Language Specification and JavaScript Dialects

 Data Types, Variables and Expressions

 Flow Control Statements

 Creating, Accessing, and Manipulating Arrays

 Defining and Calling Functions

 Web Browser Supporting JavaScript

 Server-Side and Client-Side Web Scripting

 Introduction to Objects

 Defining Your Own Object Types

 Inheritance of Properties and Methods through the Prototype Object Chain

 'jrunscript' - JavaScript Shell Command from JDK

Using Functions as "Function" Objects

 Functions Are Objects of the "Function" Type

 Using the Function Constructor

 Function Object Inherited Properties and Methods

Function Object Instance Properties

 Creating Function Objects with "function" Statements

 Creating Function Objects with the "function" Operator

 Comparing 3 Ways of Creating Functions

 Introduction to Built-in Object Types

 W3C's Document Object Model (DOM) Specifications

 References

 PDF Printing Version