Summary - Functions

JavaScript course · Beginner · Lesson 53/133

Write a VAT calculation function and call it with different amounts.

Summary - Functions

In this group you learned the basics of functions. A function is a reusable block of code; you declare it with the function keyword and call it with (). It returns a value with return; without it, you get undefined.

A parameter is the placeholder in the declaration; an argument is the value in the call. You can assign a function to a variable to create a function expression. Variables inside a function only live in that function's scope.

Exercise Write a combined function

Define a function called formatPrice. It should take an amount parameter. Inside it, declare a local variable with let result and assign it a text. Then return result. Finally print the result with console.log(formatPrice(50)).

Show example solution

function formatPrice(amount) {
  let result = amount + " USD";
  return result;
}

console.log(formatPrice(50));

Test yourself

What does this code print?
```
function calc(x) {
  return x * 2;
}
console.log(calc(5));
```
- 10
- 5
- undefined
- 2
Show answer

10 — Correct. calc(5) = 5*2 = 10 is returned and printed.
Match each concept to its meaning

return

Returns a value
parameter

Placeholder in declaration
argument

Actual value in call
scope

Where a variable lives

Complete the function declaration

function cube(____) {
  return n * n * n;
}
console.log(cube(3));

Show answer

function cube(n) {
  return n * n * n;
}
console.log(cube(3));

All lessons in Beginner

1 Variables and data types

2 Operators

3 Conditionals

Summary - Functions