Posts Tagged ‘scripting language’

What is PHP?

Thursday, July 24th, 2008

PHP is a scripting language that is often imbedded into HTML to add functions HTML alone can’t do. PHP allows you to collect, process and utilize data to create a desired output. In short, it let’s you interact with your pages.

PHP is able to preform a number of tasks including printing data, making numeric calculations (such as addition or multiplication), making comparisons (which is bigger, are they equal, etc) and making simple boolean choices. From this you can create more complex loops and functions to make your page generate more specialized data.

The JavaScript language

Wednesday, July 16th, 2008

JavaScript is not a programming language in strict sense. Instead, it is a scripting language because it uses the browser to do the dirty work. If you command an image to be replaced by another one, JavaScript tells the browser to go do it. Because the browser actually does the work, you only need to pull some strings by writing some relatively easy lines of code. That’s what makes JavaScript an easy language to start with.

But don’t be fooled by some beginner’s luck: JavaScript can be pretty difficult, too. First of all, despite its simple appearance it is a full fledged programming language: it is possible to write quite complex programs in JavaScript. This is rarely necessary when dealing with web pages, but it is possible. This means that there are some complex programming structures that you’ll only understand after protracted studies.

Secondly, and more importantly, there are the browser differences. Though modern web browsers all support JavaScript, there is no sacred law that says they should support exactly the same JavaScript. A large part of this site is devoted to exploring and explaining these browser differences and finding ways to cope with them.

So basic JavaScript is easy to learn, but when you start writing advanced scripts browser differences (and occasionally syntactic problems) will creep up.

JavaScript vs Java

Wednesday, July 16th, 2008

Although the names are much alike, JavaScript is primarily a scripting language for use within HTML pages, while Java is a real programming language that does quite different things from JavaScript. In addition Java is much harder to learn. It was developed by Sun for use in pretty much anything that needs some computing power.

JavaScript was developed by Brendan Eich, then working at Netscape, as a client side scripting language (even though there’s no fundamental reason why it can’t be used in a server side environment).

Originally the language was called Live Script, but when it was about to be released Java had become immensely popular (and slightly hypey). At the last possible moment Netscape changed the name of its scripting language to “JavaScript”. This was done purely for marketing reasons. Worse, Eich was ordered to “make it look like Java”. This has given rise to the idea that JavaScript is a “dumbed-down” version of Java. Unfortunately there’s not the slightest shred of truth in this story.

Java and JavaScript both descend from C and C++, but the languages (or rather, their ancestors) have gone in quite different directions. You can see them as distantly related cousins. Both are object oriented (though this is less important in JavaScript than in many other languages) and they share some syntax, but the differences are more important than the similarities.

If you are a C++ or Java programmer you will be surprised by some of JavaScript’s features. Since I don’t have any previous programming experience, the differences are not described on this site. The best you can do is buy David Flanagan, “JavaScript, the Definitive Guide”, 5th edition, O’Reilly, 2006. In this book the differences between C++/Java and JavaScript are clearly explained. I co–edited a few chapters of this book.