How to generate numbers?

Question

JavaScript

Hello.
Let's say I have the number 40. I need to generate a random number from 1 to 40 every 2 seconds, while it is necessary that the numbers do not repeat, how can this be done?
Here is my generation code.

const generateRandomNums = (max = 40) => {
  return Math.floor(Math.random() * (max - 1 + 1)) + 1;
};

var timerId = setInterval(() => {
  console.log(generateRandomNums());
}, 2000);

My thought:
Create an array, and before generating it, check whether there is that number in it, if so, then go to the next one. "iteration", if not, then push the number into an array and show it to the console.

Answer 1

Let's generate a generator !

function* rnd(n) {
  var nums = [], i, randomIndex, itemAtIndex;
  for( i=0; i<n; nums.push(i++));
  for( i=n-1; i>=0; i--) {
    randomIndex = Math.floor(Math.random()*(i+1)); 
    itemAtIndex = nums[randomIndex]; 
    nums[randomIndex] = nums[i]; 
    nums[i] = itemAtIndex;
  }
  i = n - 1
  while(i >= 0)
    yield nums[i--];
}


var gen = rnd(10);

while(true) {
  var v = gen.next();
  if( v.done) break;
  console.log(v.value);
}
console.log('Done!');

Answer 2

we make an array with numbers, read the number of array elements, pull a random key, while removing this value from the array.