Slide 15.21: JavaScript events (cont.)

Slide 15.20: JavaScript events (cont.)
Slide 15.22: try...catch statement
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JavaScript Events (Cont.)

onSubmit
The onSubmit event executes JavaScript code when a submit event occurs; that is, when a user submits a form. The isUpper() function will be called when the user clicks on the submit button in the form. The following script validates the information in the form and only allows it to be submitted if the requirement (lowercase letters only) is met.

The function isUpper() returns either true or false. If it returns true, the form will be submitted; otherwise, the submission will be cancelled. The notation testform.command.value, a path to find the HTML element, is from DOM (Document Object Model).

Demonstration
The following demonstration shows how the script of HTML and JavaScript is displayed on the Web.


<html> <body> <h4>Example of onSubmit Event Handler</h4> Type your name and press the button<br /> <form name="myform" onSubmit="alert('Thank you ' + myform.data.value +'!')"> <input type="text" name="data"> <input type="submit" value="Submit this form"> </form> </body> </html>

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Slide 15.20: JavaScript events (cont.)
Slide 15.22: try...catch statement
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