Using Dreamweaver To Add JavaScript To Your Web Pages
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 has a wide selection of behaviors. However, they fall into four main categories: images, windows and alerts, forms and form fields and CSS. To see how behaviors work, let us look at some examples of some behaviors in each of those 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.
In the alerts and windows category, we have Dreamweaver’s “Open Browser Window” behavior. This creates the ever-popular pop-up window. When you assign the behavior, Dreamweaver asks you to choose the HTML page you would like displayed in the window as well as the attributes you would like to add or suppress, such as scroll bars or the ability to resize the window.
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.
An example of a behavior which manipulates CSS attributes is “Show/Hide Elements”. This enables you to control the visibility of the content inside an HTML element, such as a DIV, heading or paragraph, based on user action. So, for example, when if you have a picture of a product, you can create DIVs with information on various aspects of the product and have the appropriate DIV content become visible as the user mouses over various parts of the product image.
Naturally, there is some overhead involved in using Dreamweaver’s behavior in terms of the code generated within your web page. To make your pages accessible and search engine friendly, it is recommended that you transfer JavaScript code into an external .js file and then link each of your web pages to the external JavaScript file. In Dreamweaver’s code view, highlight all of the JavaScript code between the opening and closing SCRIPT tags, then choose Cut from the Edit menu. Create an empty text file, paste in all the code and save the file with a .js file extension. Finally, in the opening SCRIPT tag on your web page type src=”myscript.js”, replacing “myscript” with the name of your file.
