create function javascript

JavaScript
function name(parameter1, parameter2, parameter3) {
// what the function does
}
var x = myFunction(4, 3);     // Function is called, return value will end up in x

function myFunction(a, b) {
    return a * b;             // Function returns the product of a and b
}function myFunction(p1, p2) {
  return p1 * p2;   // The function returns the product of p1 and p2
}// Code by DiamondGolurk
// Defining the function

function test(arg1,arg2,arg3) {
	// Insert code here.
  	// Example code.
  	console.log(arg1 + ', ' + arg2 + ', ' + arg3)
}

// Running the function

test('abc','123','xyz');

// Output
// abc, 123, xyz// variable:
var num1;
var num2;
// function:
function newFunction(num1, num2){
	return num1 * num2;
}/* Declare function */
function myFunc(param) {
  // Statements 
}
Source

Also in JavaScript: