Welcome back to part-two of our series, Tools of the Trade. Whether you’ve had a web page for years or are just now considering hanging your online shingle, the tools of the trade — and their acronyms — can be confusing. HTML, CSS, JavaScript, AJAX, PHP and MySQL are some of the technologies we use every day to build successful websites for our clients. Last time, we talked about how web browsers display HTML with CSS styles. Today we’ll learn what JavaScript and AJAX bring in to the mix.
JavaScript
JavaScript, as its name might imply, is a scripting language that the web browser interprets while loading a page and afterward. Just like your computer runs a program called FireFox or Internet Exporer, your web browser runs JavaScript programs to accomplish its tasks. Note: JavaScript is not related to the programming language Java.
Forms are a common place where the web browser will often run JavaScripts. If you’ve tried to submit a form, but were told that you’ve forgotten to fill in a particular field, then your web browser probably ran a JavaScript program to check the form input. This versatile language can find or change the value of any structural, style or content element on a web page. It can transform how information appears, show or hide different portions, and open new windows. In short, JavaScript can turn a flat page into a dynamic application.
AJAX
JavaScripts are executed by the web browser, and while this provides a lot of functionality, sometimes it’s important to go back to the server for information. Consider searching for names of movies from a database. Years ago, you would type a name into a field, press the submit button, and wait as the web browser loaded a new page with the results. No so much any more. Enter AJAX. This set of technologies lets a JavaScript on a web page retrieve information from a web server in the background and display a list of possible matches immediately, without refreshing the page. If you’ve used Facebook to search for people or Netflix to search for movies, then you’ve seen AJAX in action.
Now you should have a basic understanding of HTML, CSS, JavaScript and AJAX. So far, all of these technologies are processed by your web browser, on your own computer, also known as on the client computer. Next time we’ll look at two popular web “server” technologies – PHP and MySQL – that help make a user’s web experience even richer and more dynamic.
JavaScript
http://www.w3schools.com/JS/
AJAX
http://www.w3schools.com/Ajax/
Tags: css, javascript