Using Dreamweaver’s Interactive JavaScript Behaviors

JavaScript is a simple, client-side scripting language which enables you to add exciting and interesting functionality to your HTML pages. It is built in to most web browsers and, although it can be deactivated, most people will have it enabled within their browser. JavaScript’s uses includes the validation of entries within an HTML form and the detection of browser versions and presence or absence of plug-ins. Dreamweaver’s implementation of JavaScript centres on the use of what it calls “behaviors”.

A behavior is simply a pre-written JavaScript function which can be triggered by a given event. To make the Behaviors window visible, choose Behaviors from the Window menu. Next select the element to which you want to attach the JavaScript. Finally, choose one of the available behaviors from the menu in Behaviors window. (The behaviors which are available will depend on the item you have highlighted.)

Dreamweaver attempts to guess the event that you would like to trigger the behavior such as an onMouseOver, onClick or OnDoubleClick. If it guesses the wrong event, simply choose the correct event from the drop-down menu next to the name of the event.

Dreamweaver contains several types of JavaScript behaviors. Some relate to images, others display windows and messages, others can be used on forms and form fields and still others can be used to manipulate CSS attributes. To get a flavour of how behaviors work, let us examine a behavior in each of the above categories.

The classic example of an image manipulation behavior would be the “swapImage″ behavior. This venerable JavaScript function causes the source of a given image to change when the mouse passes over the image and back to the original when the mouse leaves the image. This behavior can either be explicitly applied to an image or can be generated automatically by inserting a rollover image.

As far as alerts and windows behaviors is concerned, as well as the simple “Pop-up Message″, which just causes a system alert box to appear, Dreamweaver also offers the more sophisticated “Open Browser Window″. This Dreamweaver behavior allows you to create a pop-up window of any specified dimension and allows you to choose the attributes of the window: the HTML file it displays, the presence or absence of the title bar, scroll bars, etc.

The key behavior relating to forms is called “Validate Form″. It performs simple checks on any text field within a given form. (It ignores any fields other than text fields.) To use it, select a field (the validation will then occur when the user leaves the field) or select the entire form (the validation will then occur when the form is submitted). Choose “Validate Form″ form the Behaviors panel menu and specify the type of validation you wish to perform, for example, ensuring that a field has not been left blank.

Dreamweaver has a number of behaviors which can be applied manipulate the CSS attributes associated with a given page element. One such behavior is Show/Hide Elements. This enables you to make the content of an HTML element visible or hidden based on an action performed by the user. You can apply this behavior to the content of an H1, DIV, P(aragraph) basically, any element that can contain stuff.

Each behavior that you choose will create one or more JavaScript functions within the head area of your page. Part of the process of optimising your website (both in terms of accessibility and search engine compatibility) is to transfer this code to an external JavaScript file and then link the web page to the JavaScript file. To do this, you need to be in Code view and locate the function(s) generated by the behavior(s) you have used on your page. Cut all of the code between the opening and closing SCRIPT tags and place it in a text file which needs to be saved with a .js extension. Next, enter an src attribute inside the opening SCRIPT tag, for example ‘SCRIPT src=”scripts.js”‘.

For more information on JavaScript training courses, visit Macresource Computer Training, an independent computer training company offering JavaScript training courses in London and throughout the UK.