Define Functions
In either form, function definitions begin with the keyword function followed by these components:
- An identifier that names the function.
- Apairofparenthesesaroundacomma-separatedlistofzeroormoreidentifiers.
- ApairofcurlybraceswithzeroormoreJavaScriptstatementsinside.
function factorial(x) {
if (x <= 1) return 1;
return x * factorial(x-1);
}
Nested Functions
In JavaScript, functions may be nested within other functions. For example:
function hypotenuse(a, b) {
function square(x) { return x*x; }
return Math.sqrt(square(a) + square(b));
}
the inner function square() can read and write the parameters a and b defined by the outer function hypotenuse().