Declarations, parameters, return and arrow functions.
✍️ 3 exercises + code challenge in this lessonA function is a reusable block of code that runs when it is called.
function name(param1, param2) { ... }name(arg1, arg2)return sends a value back and stops the function.function greet(name = "Guest")A shorter syntax: const add = (a, b) => a + b;. With one expression, the result is returned automatically.
Mastering JavaScript Functions helps you write clean and reliable JavaScript code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
<pre id="out"></pre>
<script>
const log = (...a) => document.getElementById("out").textContent += a.join(" ") + "\n";
function toCelsius(f) {
return (5 / 9) * (f - 32);
}
function greet(name = "Guest") {
return "Hello, " + name + "!";
}
const square = n => n * n;
const add = (a, b) => a + b;
log("77°F =", toCelsius(77).toFixed(1), "°C");
log(greet("Usman"));
log(greet());
log("square(9) =", square(9));
log("add(2, 3) =", add(2, 3));
</script>Check what you learned in “JavaScript Functions”.
Return the sum from the function.
function add(a, b) {
a + b;
}
Which is a valid arrow function?
Write a function double(n) that returns n * 2, then log double(21).
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