16.3. Displaying Input Fields and Getting Data from Users: prompt() Function

The prompt() function can help you get data from users. When the WMLScript interpreter encounters the prompt() function, it instructs the WAP browser to display an input field. The text entered by the user will be returned from the function. This is the syntax of prompt():

Dialogs.prompt(title, default_text);

title and default_text are the title and the default value of the input field respectively. If everything works fine, prompt() returns the text entered by the user, otherwise it returns invalid indicating an error has occurred.

The WML/WMLScript example below illustrates the usage of the prompt() function. The user will be asked to enter a number in the range 1-100. If it is outside the range, we will ask the user to enter another number.


<?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" "http://www.wapforum.org/DTD/wml13.dtd">

  <card id="card1" title="prompt() Example">
      Enter a number between 1-100:<br/>
      <input name="number"/><br/><br/>
      <a href="promptEg1.wmls#checkRange($(number))">Continue</a>

  <card id="card2" title="prompt() Example">
      The number you entered is $(number).


extern function checkRange(number)
  while (number < 1 || number > 100){
    number = Dialogs.prompt("The number is not between 1-100. Please enter again.", number);
    number = Lang.parseInt(number);

  WMLBrowser.setVar("number", number);

The parseInt() function in the above script is a new function to you. It is used to convert a string value to an integer. We will look at it in detail when we cover the Lang standard library.

The following screenshots show the result of the above WML/WMLScript example in some mobile phone browsers:

Sony Ericsson T68i

Nokia Mobile Browser 4.0

If you type 1000 in the input field and select the "Continue" anchor link, the mobile phone browser will prompt you for another number:

Sony Ericsson T68i

Nokia Mobile Browser 4.0

Enter 50 in the input field. The mobile phone browser will go to the WML card with the ID "card2":

Sony Ericsson T68i

Nokia Mobile Browser 4.0

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