Function Syntax

Function declaration

// function declaration
function myFunctionDeclaration(arg1, arg2) {
  console.log(arg1, arg2);
}
// function call:
myFunctionDeclaration("param1", "param2");

Function expression

// function expression (anonymous function, Zugriff über Variable, kein Hoisting)
const myFunctionExpression = function (arg1, arg2) {
  console.log(arg1, arg2);
}
// function call:
myFunctionExpression("param1", "param2");

Arrow function

// arrow function (anonymous function, Zugriff über Variable, kein Hoisting)
const myArrowFunction = (arg1, arg2) => {
  console.log(arg1, arg2);
}
// function call:
myArrowFunction("param1", "param2");


// different variants:
const arrowFunctionOneArgParenthesis = (arg1) => {
  // do sth.;
};
const arrowFunctionOneArgNoParenthesis = arg1 => {
  // do sth.;
};
const arrowFunctionZeroArgsParenthesis = () => {
  // do sth.;
};
const arrowFunctionZeroArgsUnderscore = _ => {
  // do sth.;
};

Explicit and implicit return

// explicit return
const sumNormal = function (num1, num2) {
  return num1 + num2;
}

// implicit return
// the return statement is automatically created:
// one line, no curly braces
const sumArrow = (num1, num2) => num1 + num2;

// log the result
const result = sumArrow(4, 18);
console.log(result);

Returning an object

(is this also an implicit return?)

// returning an object: wrap the curly braces in parentheses
const obj = value = ({key: value});