Question:

What is JavaScript?

Answer:

JavaScript is a client-side scripting language that provides for user interaction with a web page, as well as the foundation for AJAX, which allows communication with the server without having to download a new web page.

Question:

What is client-side?

Answer:

Client-side refers to the device in the presence of the user who is visiting your website, such as a computer or cell phone.

Server-side refers to the computer that delivers the web page. While it is possible to use JavaScript on some web servers, it is not a common practice at this time. Popular server-side scripts include PHP, ASP.NET, JSP, CFM..

Question:

What is interaction?

Answer:

Interaction means the website reacts to certain actions the user invokes, such as rolling the mouse over an image, or filling in data on a form. JavaScript can modify the webpage based on those actions, such as changing the image, or displaying text advising the user that the form was not filled out correctly.

Question:

Is JavaScript always available on the client-side?

Answer:

JavaScript is available in all modern browsers, including the latest web-enabled cell phones. However, some users may disable JavaScript for personal reasons.

Question:

Will my web page be broken if JavaScript is disabled?

Answer:

Best practices suggest that web pages be built for "graceful degradation", meaning the web page should be designed in such a way that if JavaScript is present, the user receives all of the bells-and-whistles, but if it is not present, the page should still deliver proper content and formatting.

For example, without JavaScript, if the user fills out a form incorrectly, she would have to submit the form and get a new page back from the server advising her of any mistakes, where as if JavaScript is present, she could be advised of her mistakes before submitting the form.

The page works properly in both cases, but performance is better with JavaScript enabled.

Question:

What is AJAX?

Answer:

AJAX, defined as Asynchronous Javascript And XML, is a technique providing for asynchronous communication between the client and the web server. It allows "partial refresh" of the current web page, without having to reload the entire page.

For example, on a slide-show web page, clicking a button might download and display a new picture on the same page, without having to download an entirely new web page.