check-uniqueness.js

const generatePseudoRandom = (from, to) => parseInt(Math.random() * to) + from;
const ids = [];
let i = 0;
let lastCollision = 0;

while (i < 20) { // up to 20 collisions
  const newId = generatePseudoRandom(1, 999999999);
  
  if (ids.includes(newId)) {
    console.error(`Collision detected after ${ids.length + 1 - lastCollision} IDs`);
    lastCollision = ids.length + 1;
    ++i;
    continue;
  }
  ids.push(newId);
}