How to randomly generate numbers without repetition in javascript?

Question

I want to generate each number between 0 to 4 randomly using javascript and each number can appear only once. So I wrote the code:

for(var l=0; l<5; l++)          


        

Answer 1

Appreciate all your help. But probably another way to generate random number in a given max range can be implemented as per below.

function generateRan(){
    var max = 20;
    var random = [];
    for(var i = 0;i<max ; i++){
        var temp = Math.floor(Math.random()*max);
        if(random.indexOf(temp) == -1){
            random.push(temp);
        }
        else
         i--;
    }
    console.log(random)
}

generateRan();

Answer 2

Generate random numbers without any range

function getuid() {
        function s4() {
            return Math.floor((1 + Math.random()) * 0x10000)

        }
          return s4() + s4();
 }
 var uid = getuid();
 alert(uid)

Answer 3

function getRanArr(lngth) {
  let arr = [];
  do {
      let ran = Math.floor(Math.random() * lngth); 
      arr = arr.indexOf(ran) > -1 ? arr : arr.concat(ran);
   }while (arr.length < lngth)
   
   return arr;
}

const res = getRanArr(5);

console.log(res);

Answer 4

One more way to do it:

for (var a = [0, 1, 2, 3, 4], i = a.length; i--; ) {
    var random = a.splice(Math.floor(Math.random() * (i + 1)), 1)[0];
    console.log(random);
}

Don't know if it's even possible to make it more compact.

Tests: http://jsfiddle.net/2m3mS/1/

Here is embed demo:

$('button').click(function() {
    $('.output').empty();
    
    for (var a = [0, 1, 2, 3, 4], i = a.length; i--; ) {
        var random = a.splice(Math.floor(Math.random() * (i + 1)), 1)[0];
        $('.output').append('<span>' + random + '</span>');
    }
    
}).click();

.output span {
    display: inline-block;
    background: #DDD;
    padding: 5px;
    margin: 5px;
    width: 20px;
    height: 20px;
    text-align: center;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="output"></div>
<button>Run</button>

Answer 5

So many solutions to this! Here's my code for a reuseable function that takes in 3 arguments: the number of integers wanted in the array (length) and the range that the array should be comprised of (max and min).

function generateRandomArr(length, max, min) {
  const resultsArr = [];
  for (let i = 0; i < length; i++) {
    const newNumber = Math.floor(Math.random() * (max - min)) + min;
    resultsArr.includes(newNumber) ? length += 1 : resultsArr.push(newNumber);
  }
  return resultsArr;
}

generateRandomArr(10, 100, 0);
// this would give a list of 10 items ranging from 0 to 100
// for example [3, 21, 56, 12, 74, 23, 2, 89, 100, 4]