Random Numbers JavaScript

Question

<head>
<script>
function getRandomArbitrary(min, max) {

    var r = Math.floor(Math.random() * (max - min + 1) + min);
    document.getElementById('demo').innerHTML = r; 
}
</script>
</head>

<body>
<h1>randomize</h1>
  a: <input type="text" id='low'><br>
  b: <input type="text" id='high'><br>
  <button onclick="getRandomArbitrary(document.getElementById('low').value,document.getElementById('high').value)">Get</button>


<div id='demo'></demo>
</body>

I have above code, through which I am trying to generate random number between range given in texts a and b. when I manually pass the values to this function (say 10,15) it works properly (giving, say 13). but when I press the button and ask it to get value from text and calculate the random number in that range it fails to do so and calculates number which is out of range(sometimes).

I have spent a lot of time on it and couldn't see what is the problem. Please help me.

Krishnakumar_Muraleedharan · Accepted Answer · 2016-07-04 06:47:20Z

4

@Ojas Kale, first things first. Min and max are being passed strings. Try parsing them into integers first.

getRandomArbitrary(parseInt(document.getElementById('low').value),parseInt(document.getElementById('high').value));

Also I please modify the getRandom function as below. No need to round the sum right?

function getRandomArbitrary(min, max) {

    var r = Math.floor(Math.random() * (max - min + 1) )+ min;
    document.getElementById('demo').innerHTML = r; 
}

answered Jul 4, 2016 at 6:47

Krishnakumar_Muraleedharan

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Comments

Rayon · Accepted Answer · 2016-07-04 06:43:11Z

3

Cast the value as Number and then pass to function

Unary plus (+), The unary plus operator precedes its operand and evaluates to its operand but attempts to converts it into a number, if it isn't already.

function getRandomArbitrary(min, max) {
  var r = Math.floor(Math.random() * (max - min + 1) + min);
  document.getElementById('demo').innerHTML = r;
}

<h1>randomize</h1>
a:
<input type="text" id='low'>
<br>b:
<input type="text" id='high'>
<br>
<button onclick="getRandomArbitrary(+document.getElementById('low').value,+document.getElementById('high').value)">Get</button>
<div id='demo'></div>

answered Jul 4, 2016 at 6:43

Rayon

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1 Comment

Ojas Kale Over a year ago

Perfect. Works fine Now. Thanks a lot.

Francesco Taioli · Accepted Answer · 2016-07-04 06:40:27Z

1

Math.floor(Math.random() * max) + min

answered Jul 4, 2016 at 6:40

Francesco Taioli

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1 Comment

Ojas Kale Over a year ago

the problem is not with the logic of finding random number. problem lies somewhere when I pass the value from html page.

user2321864 · Accepted Answer · 2021-01-31 15:55:48Z

0

var min = (your minimum number value);
var max = (your maximum number value);
var myRandom = Math.floor(Math.random() * max) + min;

To get random number as an integer between two number, you can use the function; Thanks to this function you will generate an integer between min and max

edited Jan 31, 2021 at 15:55

user2321864

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answered Jan 31, 2021 at 10:25

Hayris

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