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Thursday, November 15, 2007

An introduction to Javascript for web designers

If you are creating a web site for the first time, then you probably have some knowledge of the HTML programming language. HTML is a fairly simple language to learn, and most beginning web designers are usually self-taught when it comes to using HTML to create a simple site. HTML provides the style, structure, and formatting for a web site.

However, HTML does not actually do anything. It is a static programming language. It does not process anything or make your site interactive, it just sits there and tells the browser how the site should look. So, other programming languages have been created to not only improve site design, but to validate forms, establish cookies to make sites easier to use, and to react to input received from the user.

One such language, perhaps the most important and widely used non-static programming language, is called Javascript. Javascript, contrary to its name, has virtually nothing to do with the Java programming language. Javascript is a scripting language. Scripting languages are used to connect diverse pre-existing parts to accomplish a new related task without compiling. Instead, scripting languages are interpreted, and are executed faster than a compiling language. Javascript is very versatile and can communicate with other languages effectively. Javascript is a registered trademark of Sun Microsystems, and is compatible with every major browser on the market.

Javascript is most often used to handle certain events that might take place as the user interacts with the web page. For example, if the user is filling out an online form on the site and enters invalid information into one of the form fields, then javascript can be programmed into the website to check the validity of the input before the form is submitted. If the input is invalid, the script can be used to prevent the form from being submitted and to tell the user what needs to be corrected.

Javascript, when used, is ordinarily inserted in the head section of the web page. In the head section, the programmer can create certain functions that can be executed if that function is called upon somewhere in the body section of the page. Using the form example once again, if there is an HTML form somewhere on the page, the programmer may want to create a Javascript function to insure that the user enters his or her last name before the form can be submitted. To accomplish this, the function must be inserted in between the opening and closing head tags of the web page. Then, the function must be called upon within the form tag of the HTML form. Then, when the user tries to submit the form, the form tag calls upon the Javascript function in the head section to make sure that the last name has been entered. If the last name was omitted, then the submission is halted and the user is told to enter his or her last name before submitting the form.

Like any mathematical function, Javascript functions also make use of variables and arithmetic operators. The logic of Javscript functions is often created using if/then statements so that if a certain condition exists, then a certain reaction or output will result. Uses for these functions include form validation, enabling cookies, displaying certain images when the user performs a certain action, and detecting what kind of web browser the user has so that the style of the web page can be instantly adjusted to accommodate that particular browser.

Javascript is actually a fairly easily language to learn, because it is very logical and the syntax is not complicated. Even if you have never used Javascript before, you can learn it fairly easily by searching for tutorials on any major search engine. Using Javascript will bring your static HTML web pages to life.

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