Lesson · Chapter: Functions+10 XP for reading
Building Your Own Commands
Functions let you create your own reusable blocks of code, like building your own commands!
Defining a Function
Use the function keyword to create a function:
javascript
function greet() {
console.log("Hello there!");
}
greet();
Output
Press Run to see the output.
Output:
Hello there!
The code inside the braces runs every time you call the function with greet().
Functions with Parameters
Parameters let you pass information to a function:
javascript
function greet(name) {
console.log(`Hello, ${name}!`);
}
greet("Alex");
greet("Sam");
Output
Press Run to see the output.
Output:
Hello, Alex! Hello, Sam!
Returning Values
Use return to send a value back:
javascript
function double(n) {
return n * 2;
}
let result = double(5);
console.log(result);
Output
Press Run to see the output.
Output:
10
Multiple Parameters
Functions can take more than one parameter:
javascript
function add(a, b) {
return a + b;
}
console.log(add(3, 4));
Output
Press Run to see the output.
Output:
7
Why Use Functions?
Without functions, you'd repeat the same code over and over:
javascript
// Without functions — lots of repeated code
console.log("Hello, Alex!");
console.log("Hello, Sam!");
console.log("Hello, Jordan!");
// With functions — much cleaner!
function greet(name) {
console.log(`Hello, ${name}!`);
}
greet("Alex");
greet("Sam");
greet("Jordan");
Output
Press Run to see the output.
Functions make your code shorter, cleaner, and easier to fix!