JAVASCRIPT

a function that calls itself js

(function(){
    for (let i = 1; i < 20; i++){
      if ((i % 2) === 0) console.log(i + ' ');
    }
  })();

//you don't have to call it, it'll just show you the result

a function that calls itself js

(function foo() { foo(); })();

js function call itself

// JavaScript Recursive Function:
// A recursive function is a function that calls itself until it doesn't.
function sumArray(array) {
  let sum = 0;
  for (const item of array) {
    sum += Array.isArray(item) ? sumArray(item) : item;
  }
  return sum;
}
sumArray([1, [4, 6]]); // => 11