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.)

You will also need to ensure that the correct event (click, double-click etc.) is linked to the behavior. Dreamweaver will always assign an event automatically. However, if this event is not the one you actually want, just select a different event by clicking on the drop-down menu located to the right of the name of the event in the Behaviors panel.

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.

Perhaps the most frequently encountered JavaScript function is one that changes the appearance of an image when the mouse passes over it. Dreamweaver creates this functionality with the “Swap Image” behavior. You can also add this behavior automatically by choosing Insert – Image Objects – Rollover Image. Dreamweaver automatically adds a second behavior/function called “Restore Image” which changes the image back to the original when the mouse leaves the image.

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.

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 contains a couple of very useful behaviors which manipulate the content of HTML elements. To use these, you need to give the element and ID (for example). The DIV element offers the greatest flexibility when using this behavior since it can contain just about anything you want. You highlight the element which will trigger the behavior and then choose Show/Hide Elements from the Behaviors panel menu. Click on any listed element then click either the Show or Hide button.

If you have used several JavaScript behaviors on a page, you may find that the amount of code generated by Dreamweaver becomes quite significant. It is therefore usually a good idea to place all of this code in an external JavaScript file and then link this file to your page. To do this, click on the “Code” button in the top left of the page and locate the SCRIPT tags which contain the JavaScript. Select all of the code between the SCRIPT tags and cut it to the clipboard. Next, create a blank file with the file extension .js and paste all of the code inside it. Finally, to link your page to the .js file, position your cursor inside the opening SCRIPT tag and type src = “myfile.js” substituting the name of your JavaScript file for “myfile.js”.

If you would like to learn more about JavaScript training courses, visit Macresource Computer Training, a UK IT training company offering JavaScript training courses at their central London training centre.

categories: Dreamweaver,Adobe Dreamweaver CS3,JavaScript,behaviors,web development,website accessibility,computers and the internet,computer software

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