console time for performance

console.time("for");
let sum = 0;
for (let i = 0; i < 1e4; ++i) {
  sum += i;
}
console.log(sum);
console.timeEnd("for");

console.time("while");
sum = 0;
let i = 1e4;
while(--i) {
  sum += i;
}
console.log(sum);
console.timeEnd("while");