Most programs use variables. This lesson explains what variables are.
length returns the number of elements in an array. Right? Er, well, ...
Create a quiz about yourself.
You’ll learn how to use
focus() to improve a page’s usability.
- Learn how to set the text of an element, with
- Learn how to get the text of an element, with
- Learn how to add a CSS class to an element, with
- Learn how to remove a CSS class from an element, with
In this lesson, you will learn that:
- Some programs run inside browsers.
- Those programs are downloaded along with pages.
- Programs are triggered by events.
- Syntax bugs happen when you type something the browser doesn’t understand, like
- Use Firefox’s error console to track down syntax errors.
- Logic errors are when you tell the browser to do the wrong thing.
alert()statements to track program execution. If
alertmessages are supposed to show up, but don’t, you know what code is not executing.
alert()statements to look at the values of variables.
- How to report errors in a professional way.
- How page-wide, global error messages help the user.