function
Declares a named function that is hoisted within its scope.
Syntax
function name(param1, param2) {
// body
}
Returns
undefined — A function declaration is a statement and does not itself produce a
value; calling the function may return a value.
Examples
function add(a, b) {
return a + b;
}
console.log(add(2, 3));
Output
5
// Function declarations are hoisted
console.log(square(4));
function square(n) {
return n * n;
}
Output
16
function greet(name = "world") {
return "Hello, " + name;
}
console.log(greet());
Output
Hello, world
Notes
- Function declarations are hoisted with their definition, so they can
be called before they appear in the source.
- A function declaration creates a binding in the enclosing scope.
- Use a function expression or arrow function when you need a function
value assigned to a variable.
Browser & runtime support
| Environment | Since version |
|---|---|
| chrome | 1.0 |
| firefox | 1.0 |
| safari | 1.0 |
| edge | 12 |
| node | 0.10 |