Summary - Functions
- JavaScript course
- Beginner
- Lesson 53/133
- 5 min
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.
Practice 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)).
Starter code
// Define the formatPrice function here
// It takes an amount parameter
// Create a result variable inside
// Return the result variable
// Print the resultSample solution
function formatPrice(amount) {
let result = amount + " USD";
return result;
}
console.log(formatPrice(50));Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does this code print?
function calc(x) {
return x * 2;
}
console.log(calc(5));- 5
- 10 Correct answer
- undefined
- 2
Explanation: calc(5) = 5*2 = 10 is returned and printed.
2 Match each concept to its meaning
| Term | Meaning |
|---|---|
return |
Returns a value |
parameter |
Placeholder in declaration |
argument |
Actual value in call |
scope |
Where a variable lives |
3 Complete the function declaration
function cube(____) {
return n * n * n;
}
console.log(cube(3));function cube(n) {
return n * n * n;
}
console.log(cube(3));Explanation: cube(n) takes an n parameter.