JavaScript first emerged in 1996 and was a programming language written by Brendan Eich for Netscape. Initially, it was developed so the code could be embedded in Web pages so it could process numbers and modify the contents of forms. Over the years, the use of JavaScript code has increased exponentially and is now used in a great many ways, including image manipulation and mouse-over effects etc. Although it is now such a popular programming language in it's own right, there are few minor niggles and issues to be aware of.

Advantages

Speed - because all the code resides on what is known as the 'client-side', response times are fast. The alternative to client-side is known as 'server-side' and this involves your computer having to wait for a response from a command or instruction to a computer server somewhere out on the Web.

Simplicity - JavaScript as a computer language is not too difficult to learn and there are stacks of resources available on the Internet to help you. It is also possible to download masses of high quality code example free-of-charge and this can help you to reduce time demands and also to assist you in understanding the language dynamics.

Versatility - Unlike PHP and SSI scripts for example, JavaScript is highly co-operative with other computer languages and can be used in conjunction with a great many applications. Another good thing about JavaScript is that it can be inserted in any web page irrespective of your chosen extension (e.g .htm, .html & .php etc.).

Load on servers - Because it is client-side, there is no demand placed on the server where the website resides.

Disadvantages

Security - An important consideration is that because the JavaScript code is executed on the user's computer, there is a chance of it being exploited in a malicious way. For this reason, some people cautiously disable JavaScript from operating on their computer. This is not the major consideration, but it is worth bearing in mind as you develop Web applications.

Browser incompatibility - An ongoing problem is that JavaScript can be interpreted in different ways by the various browsers. The most important thing is that you verify the operation of your JavaScript code in the major browsers and do not get too hung up about the rest.