Adding Dreamweaver Behaviors To Your Web Pages

JavaScript is a well-established scripting language which creates code that can execute both an HTML page loads and after it has loaded. It is very efficient since it can run independently on the computers of the visitors to your web site. Thus freeing up your server to do other things. It is so widely used on web sites that, though it is possible for a user to disable JavaScript within their browser settings, most people will need to leave it active if they are to interact with the sites they visit. Adobe Dreamweaver allows web developers to add JavaScript to their pages by using what it refers to as "behaviors".

A Dreamweaver behavior is an automatically generated JavaScript function which is activated by a given user or browser action. To use behaviors, choose Window > Behaviors. Before attaching a behavior, you must highlight one of the elements on your page such as a hyperlink or image. Then you need to choose a behavior by clicking on the plus sign in the top left of the Behaviors window.

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's behaviors fall into four main categories: manipulation of images, alerts and windows, form field handling and CSS handling. To get a feel for how behaviors work, let's take an example of a behavior in each of these categories.

There was a time when almost every website featured the rollover effect on its navigation buttons. With the development of CSS, this is no longer the case. However, the facility of having an image change appearance when the mouse passes over it is still useful. Dreamweaver achieves this effect with the "Swap Image" behavior which can either be added to an image or can be created automatically by inserting a rollover image (Insert > Image Objects > Rollover Image) rather than a static one.

Dreamweaver's "Open Browser Window" behavior allows you to create the controversial JavaScript pop-ups. Due to its extensive misuse, many people have developed an extreme intolerance of this feature. However, there are situations where it is useful. For example, if a user is in the middle of filling out a form and clicks a help icon next to a certain item, a pop-up window is an ideal method of displaying the help topic.

In the form manipulation behaviors category, we have "Set Text of Text Field" and "Validate Form". The "Validate Form" behavior only applies to text fields and enables you to ensure, first of all, that a field has not been left blank; secondly, that a field contains a valid email address; thirdly, that a field contains a numeric value; and, fourthly, that a field contains a number within a given range.

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