Generate unique random numbers between 1 and 100

Question

For example: To generate 8 unique random numbers and store them to an array, you can simply do this:

var arr = [];
while(arr.length < 8){
    var r = Math.floor(Math.random() * 100) + 1;
    if(arr.indexOf(r) === -1) arr.push(r);
}
console.log(arr);

1. Populate an array with the numbers 1 through 100.
2. Shuffle it.
3. Take the first 8 elements of the resulting array.

Modern JS Solution using Set (and average case O(n))

const nums = new Set();
while(nums.size !== 8) {
  nums.add(Math.floor(Math.random() * 100) + 1);
}

console.log([...nums]);

Another approach is to generate an 100 items array with ascending numbers and sort it randomly. This leads actually to a really short and (in my opinion) simple snippet.

const numbers = Array(100).fill().map((_, index) => index + 1);
numbers.sort(() => Math.random() - 0.5);
console.log(numbers.slice(0, 8));