5.4.1 Reading — Methods: functions that live on a class

Methods: functions that live on a class

Read before 2.2.7b Lab — Method with no params. About 4 minutes.

By the end of this reading you should be able to answer:

• How does a method declaration differ from a function declaration?
• Can you spot a method in a 6-line class body?

A method is a function that lives inside a class body and has access to this. The only syntax difference from a regular function is that you drop the function keyword.

What you'll learn from it:

• Inside a class body, write methodName(params) { ... } — no function keyword.
• Adding function before the method name is a syntax error; the engine won't run the file.
• A method is available on every instance of the class — you don't create it separately.
• Calling a method on an instance: instance.methodName(args).

Try it:

What you'll see: distance = 5. The distanceTo method is called on a with b as the argument.

Try this: in the editor above, add the word function before distanceTo (so it reads function distanceTo(other) {). Click Run and watch the on-canvas console. You'll see a syntax error. Remove function again and confirm it works.

Short glossary (quick reference)