Declare a function

Describes how to declare and use a function.

A function is a collection of codes that perform specific tasks. If repeated tasks exist, you can create and reuse functions to create more efficient and manageable code.

There are many ways to declare a function in JavaScript, but we recommend using an arrow function in Redbrick Studios.

The arrow function can be declared in the form const foo = (a) => {console.log(a)} and executed in the form variable name.

// arrow function declaration
const add = (num1, num2) => {
  const sum = num1 + num2;
  console.log(sum);
};
 
add(1, 2); // 3

The return keyword can be used internally to stop the function from running and return the value declared after it.

const add = (num1, num2) => {
  const sum = num1 + num2;
  console.log(sum);
};
 
const sum = add(1, 2);
 
console.log(sum); // 3

Variables declared as let and const within a function cannot be accessed outside the function, but variables declared outside the function can be accessed inside the function.

const outerValue = 1;
 
const someFunction = () => {
  const innerValue = 2;
 
  console.log(outerValue);
};
 
console.log(innerValue); // Error!
console.log(someFunction()); // 1