How to randomize number without repitition within a range

Question

For example: The range is 20
There's a button which randomizes a number.
It should result to a 20 random numbers from 1 to 20 without repeating if I clicked the button 20 times.
Program to use: JavaScript or jQuery

https://code.sololearn.com/W0g2I7uDP58v/?ref=app

Answer 1

function randomNumbersArray(n) {
var nums = [], num;
for (var i = 0; i < n; i++)
{
do {
num = (Math.floor(Math.random() * n));
} while (nums.indexOf(num)!=-1)
nums.push(num);
}
return nums;
}

var randomNumber20 = randomNumbersArray(20);

https://code.sololearn.com/W7Lm9Ufx4cna/?ref=app