Pattern catalog

Patterns are common ways of doing things, like recipes. People have patterns for solving equations, making web pages, wrapping gifts, all sorts of things. Part of learning a skill is learning the patterns that help you be more effective.

Here are patterns on this website. This list can help you find the patterns you need to do a task.

Name Tags Summary Where referenced
Accumulate error messages

Make a variable for error messages. Append all messages to that variable.

More conditions
Basic page template HTML

A template for a basic page.

Page template
Break down complex conditions

Businesses often have complex rules. That can lead to code that is complicated, and hard to read. Use boolean variables for individual conditions. Your code will be easier to think about.

More conditions
Computation at the top, simple output at the bottom

Put code for complex calculations in the top part of your program. That code puts values in variables. The bottom bit makes HTML using those variables.

More conditions, Images , Conditional styles, Validation basics
Error messages as a flag

Use a variable containing error messages as a flag. If it's MT, no errors.

More conditions, Conditional styles
Flag

Use a variable as a flag. Set the flag if any of a number of things happens. After, check the flag to see if any of those things happened.

More conditions, Checking permissions, Log in/out, Validation basics
Multifield validation

For each input to check:

Combine the error messages for each field.

Multifield validation
Multiway if

Make a chain of ifs and elseifs for a variable that can have several different values.

Conditional styles
Same page validation Forms

Put a form and its validation code on the same page.

Log in/out, Same-page validation
Separate input from processing Forms

Put input and validation in one program. Put processing code in another. Use the session to send data from one to the other.

Beginning forms