JavaScript Functions

A function is a reusable recipe.

You write the steps once. Then you call the recipe whenever you need it.

Think of a cookie cutter. Same shape. Many cookies.

Function declaration

Write function, then a name, then parentheses, then a block.

Parameters and arguments

Parameters are empty slots in the recipe.

Arguments are the real values you pass in.

Return

return sends a value back out.

After return, the function stops.

Function expression

You can store a function in a variable.

Arrow function

Arrow functions are a shorter style.

They are common for tiny helpers.

Default parameters

You can give a fallback value if no argument arrives.

Tip: Keep functions small. One clear job per function is easier to test and reuse.