How to create 3 unique values from an array of characters

Question

can you please take a look at this demo and let me know how I can create 3 unique values from an array of numbers?

var num = [];
var chances = "0123456789";
for (var i = 0; i < 3; i++) {
  num.push(chances.charAt(Math.floor(Math.random() * chances.length)));
}

console.log(num);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Why not just Math.floor((Math.random() * 10)) and as the values are random, that doesn't mean it should be unique, especially when creating a single-digit random value — Tushar
– Tushar, Commented Oct 6, 2015 at 5:26
Hi Tushar I already tried it but was n't sure how o limit the number of selected item to 3?! — Behseini
– Behseini, Commented Oct 6, 2015 at 5:31
Do you want three unique characters from your string with no repeats? What you have is not actually an array of characters - it's a string. — jfriend00
– jfriend00, Commented Oct 6, 2015 at 5:31
Unique randoms here: unique random array javascript and Generating random numbers on different input texts and ensuring random numbers shown are unique and Javascript generate random unique number every time. — jfriend00
– jfriend00, Commented Oct 6, 2015 at 5:34

Pranav C Balan · Accepted Answer · 2015-10-06 06:16:30Z

2

You can do something like this

var num = [];
for (var i = 0; i < 3;) {
  var ran = Math.floor(Math.random() * 10);
  //  You can generate random number between 0-9 using this , suggested by @Tushar
  if (num.indexOf(ran) == -1)
  // check number is already in array
    num[i++] = ran;
    // if not then push the value and increment i
}

document.write(num.join());

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

For getting unique alphabets

var res = [],
  alp = 'abcdefghijklmnopqrstuvwxyz'.split('');
  // creating an array of alphabets for picking alphabers
for (var i = 0; i < 3;) {
  var ran = Math.floor(Math.random() * 26);
  //  You can generate random number between 0-25 using this
  if (res.indexOf(alp[ran]) == -1)
  // check alphabet is already in array
    res[i++] = alp[ran];
  // if not then push the value and increment i
}

document.write(res.join());

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Or

var res = [],
  alp = 'abcdefghijklmnopqrstuvwxyz'.split('');
  // creating an array of alphabets for picking alphabers
for (var i = 0; i < 3;) {
  var ran = Math.floor(Math.random() * 10000) % 26;
  //  You can generate random number between 0-25 using this
  if (res.indexOf(alp[ran]) == -1)
  // check alphabet is already in array
    res[i++] = alp[ran];
  // if not then push the value and increment i
}

document.write(res.join());

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

edited Oct 6, 2015 at 6:16

answered Oct 6, 2015 at 5:33

Pranav C Balan

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5 Comments

Behseini Over a year ago

Thanks Pranav C Balan, can you also let me know hoe to get 3 unique letter from alphabet as well?

Tushar Over a year ago

That's a nice work-around @Behseini but keep in mind this does not generate random unique numbers, this'll just pick unique numbers from random numbers

Tushar Over a year ago

@Behseini You cannot generate random numbers that are unique.

Behseini Over a year ago

Ok I think I understand what you are saying now

Pranav C Balan Over a year ago

@Behseini : developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

user2575725 · Accepted Answer · 2015-10-06 05:59:38Z

0

You may also try this code:

var num = [];
var chances = "0123456789";
var len = chances.length;
var str;
while (num.length < 3) {
  str = "";
  while (str.length < len)
    str += chances[Math.floor((Math.random() * len) % len)];
  if (-1 === num.indexOf(str))
    num.push(str);
}
document.write(JSON.stringify(num));

answered Oct 6, 2015 at 5:59

user2575725

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