IT 130

Here are some simple examples using JavaScript:

• Simple greeting page
• Greeting page with output in text area
• Story setting with text area
• Temperature conversion
• Story setting with HTML output

Here are some useful tips and references:

• JavaScript is case-sensitive. Generally, you will need to type all commands in lower-case in order for your JavaScript to work.
• Be careful where you start and close quotes for creating literal strings.
• The online tutorials often use document.write for output. However, we won't use that in this class since it's not useful for creating interactive pages.
• Use JavaScript comments to explain what your JavaScript code does.
• Most input methods (e.g. prompts and text fields in forms) produce a string. If you want a number, you may need to convert the string to a number using parseFloat.

• Types of errors
• Syntax error occurs when page loads, usually a typing error
• Run-time error occurs when a statement is executed
• Logic error causes incorrect output
• Delete (or "comment out") suspect code
• Using the alert function to trace code
• Help from Text Editor (e.g. Brackets)
• Color coding shows strings
• Matching parentheses are marked
• Check HTML code
• Help from browsers
• Google Chrome: Menu Icon (upper right, by the star) --> More Tools --> Developer Tools --> Console
• Firefox: Menu icon (upper right) --> Developer --> Web Console
• Internet Explorer: Tools --> Internet Options --> Advanced tab --> select Display a Notification about Every Script Error

What's wrong with this page?

Find the bugs in this tip calculator page.

Here's a simple page that uses a predefined square-root function. Here's a reference to predefined functions (look under JavaScript Math Objects and Javascript Global Properties and Functions for the most common functions).

Dave Reed has created a library of useful random functions. Here is one example that uses the random functions. Here's a link to these functions.