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JavaScript

Posted by rocky roy
rocky roy
556 Points

document.getElementByID.innerHTML = 'example' ; showing nulll

function RandomNo(upper) { return Math.floor(Math.random() * upper) + 1; } var i = 0; while (i < 100) { var HoldRandomNo = RandomNo(10); document.getElementById('demo').innerHTML = HoldRandomNo + ' '; i += 1; }

3 Answers

jcorum
jcorum
71,830 Points
jcorum
jcorum
71,830 Points

rocky, not sure if this is the issue, as you didn't give a copy of your html, but in order for this line of code to work:

document.getElementById('demo').innerHTML = ...;

there must be an element in the html, and only one element, whose id is demo ( <... id="demo" ...></...>

jcorum
jcorum
71,830 Points
jcorum
jcorum
71,830 Points

rocky, I ran your code in an online JavaScript tester (https://jsfiddle.net/) with the body element you sent (you don't need your html or head as they supply their own), and it ran fine. Each time the result was a different random number.

Here's the html I used:

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

And here's the Javascript:

function RandomNo(upper) { 
   return Math.floor(Math.random() * upper) + 1;
} 
var i = 0; 
while (i < 100) { 
  var HoldRandomNo = RandomNo(10); 
  document.getElementById('demo').innerHTML = HoldRandomNo + ' '; 
  i += 1; 
}

I'm puzzled by your code.

You loop 100 times, but display each of the 100 random numbers on top of the previous one, so that at the end you have only 1 number displayed on the page. And because modern computers run so fast, you don't even see the numbers change.

So why the loop? Just testing loop code? Or?

But anyway, it runs without error. So the null must be from some other problem.

rocky roy
rocky roy
556 Points
rocky roy
rocky roy
556 Points 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
   <div id="demo"></div>

    <script src="script.js"></script>
</body>
</html>