js how to put 20 random numbers in array code example

Example 1: javascript generate array of random different numbers

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);

Example 2: generate an array of random numbers javascript

let numbersArray = [] , max = 100;

for( var i=1; numbersArray.push(i++) < max;);  // numbers = [1,2,3 ... 100]