JavaScript > Basics

Now we're going to get onto the dynamic parts of JavaScript. Events are occurrences triggered by a user interacting with your page, whether it be clicking on something or just moving their mouse around. By the end of this tutorial you'll have things responding to all sorts of user interactions.

One of the primary reasons JavaScript was assembled was to check whether the values entered into forms by readers were correct, thereby bypassing the lengthy trip to a CGI program to do the check. Here we'll learn the methods used to validate form input, using the onSubmit event handler.

Regular expressions are, in short, a way to effectively handle data, search and replace strings, and provide extended string handling. Often a regular expression can in itself provide string handling that other functionalities such as the built-in string methods and properties can only do if you use them in a complicated function or loop.

Create a flashing text effect

A simple JavaScript tutorial showing how to replace an image when the cursor rolls over it.

Sometimes it's useful to add a popup to your pages. When the user clicks on a link, a new window opens and displays a page.

The isNaN() function is used to check if a value is not a number.

The Date object is useful when you want to display a date or use a timestamp in some sort of calculation. In java you can either make a Date object by supplying the date of your choice, or you can let Javascript create a Date object based on your visitor's system clock. It is usually best to let Javascript simply use the system clock.

On this page I explain what strings are and then give an overview of some useful things you can do with them.