# 14. WMLScript Standard Libraries Overview

WMLScript is based on ECMAScript, which is the standardized version of JavaScript. However, some functionality of ECMAScript has been taken away in order to increase the efficiency of WMLScript. To keep WMLScript sufficiently powerful, a number of standard libraries are added to it. Functions in the WMLScript standard libraries can perform tasks that cannot be easily implemented or are impossible to be implemented by writing your own WMLScript code.

There are six standard libraries totally. Here is an overview of them:

1.
WMLBrowser library

The WMLBrowser library provides a group of
functions to control the WML browser or to get information from it.

2.
Dialogs library

The Dialogs library contains functions for
displaying alert messages, confirmation messages and input boxes to
users.

3.
String library

The String library provides a number of functions
that help us manipulate strings.

4.
Float library

The Float library contains functions that help us
perform floating-point arithmetic operations.

5.
Lang library

The Lang library provides functions related to the
WMLScript language core. It contains functions for generating random
numbers, performing some arithmetic operations and dealing with data
type conversion.

6.
URL library

The URL library contains functions that help us
manipulate URLs.

The WMLScript standard libraries are included in the WAP specification. Hence, mobile devices that support WMLScript should also support the WMLScript standard libraries. Note that the Float library is only available on mobile devices that can perform floating-point calculations.

WMLScript programmers should get familiar with the standard libraries. With such knowledge, you can know whether a particular task can be done by using the functions in the standard libraries. If the standard libraries do not have the function you need, that means you have to implement the function yourself or the task cannot be done with the WMLScript language.

## 14.1. How to Call a Function in the WMLScript Standard Libraries

Calling a function in the WMLScript standard libraries is simple. It is the same as calling your own function, except that you have to add the library name and a dot character before the function name. This is the syntax:

*library_name*.*function_name*(*parameter1*,
*parameter2*...);

The
following WMLScript example demonstrates how to call the *sqrt()*
function of the Float standard library to calculate the square root
of a number:

function
findSquareRoot(number)

{

return Float.sqrt(number);

}

In the following sections, we will introduce to you each of the standard libraries and provide an in depth coverage of the commonly used functions.

Previous Page | Page 30 of 71 | Next Page |

**Click Here for Full Table of Contents**)

- 1. WMLScript Introduction
- 2. Hello World WMLScript Example
- 3. Compiling WMLScript Code
- 4. WMLScript Language Rules
- 5. Defining WMLScript Functions
- 6. Calling WMLScript Functions
- 7. WMLScript Variables
- 8. WMLScript Data Types
- 9. WMLScript Variables Vs WML Variables
- 10. Passing Arguments to Functions By Value and By Reference
- 11. WMLScript Operators
- 12. WMLScript Conditional Statements
- 13. WMLScript Looping Statements
- 14. WMLScript Standard Libraries Overview
- 15. WMLScript WMLBrowser Standard Library
- 16. WMLScript Dialogs Standard Library
- 17. WMLScript String Standard Library
- 18. WMLScript Float Standard Library
- 19. WMLScript Lang Standard Library
- 20. WMLScript URL Standard Library
- 21. WMLScript Example: Validating Form Data