Introducing JavaScript

JavaScript has changed a great deal since it was first introduced but many sites still use outdated techniques. There are even lots of JavaScript tutorials on the web that show you how JavaScript should be written so that it can work in Netscape 2 rather than so that it will work in modern browsers. As a result there are many people who are writing what they think is JavaScript but where what they are producing is more suited to the 20th Century than to the 21st.

Beginners should work through all the basic examples prior to moving on to the other examples which cover separate aspects of JavaScript in more detail.

Most of the JavaScript examples here will work in IE5+, Opera7+ and all versions of Firefox, Safari and Chrome. Those commands introduced in ECMAScript 5 in 2011 are being added to the site where they are supported by the latest version of all popular browsers. Where these new commands are not supported by IE8 or IE7 that information is included in the text since those two browsers might still have to many users for you to ignore. So few people using other browsers fail to keep their browser up to date that lack of support in older versions of other browsers will not have any significant affect.

A few examples of what we can expect from EcmaScript 6 are also included in their own section so you can see the direction that JavaScript is moving in - even though it will probably be quite a while before we can use those commands.

There is a link to jsBin at the bottom right of all the pages. This site provides an easy way to test your JavaScript code online without needing to create an entire web page to run a simple test.


Unlike parseInt, parseFloat only takes one parameter and is intended for converting strings into numbers, although the numbers it is intended to convert from strings are generally those that are either very large or very small and so need to use exponential notation to enter them.


The parseInt function is intended for converting numbers in any number base between 2 and 36 into the base 10 equivalent.As a side effect it also discards any characters on the end of the supplied string that cannot be interpreted as numbers and so can also be used to strip the type of measure from […]


The String function converts any variable into the string equivalent. When called with primitive values it will convert to a simple text string. When you pass an object then that object’s toString method will be called to do the conversion.


The Number function is what you call to convert any variable to a number. You can also call this function implicitly when you pass variables into operations that only work with numbers.


To obtain the current date and time as a text string without having to create a Date object you can simply call the Date function.

This site is © copyright Stephen Chapman - Felgall Pty Ltd 2011-2015.

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You are welcome to use any the example JavaScript from this site in the scripts for your site or any that you develop for others but may not use the longer example scripts that contain a copyright notice in any other way without permission.