How do you create a for loop using a variable in javascript?

Question

I have a block of code under a div element "questionform" and want to allow the code to repeat, depending on the number of times the user would like it to, to eventually allow the user to make a quiz. I have tried to create a bit of javascript in order to repeat just the question number for now, but it won't work.

<div id="myHTMLWrapper">

</div>

<script>
  var wrapper = document.getElementById("myHTMLWrapper");

  var number = prompt("Enter the number of questions");

  for (var i = 0; i = number - 1; i++) {
    myHTML += '<span class="test">Question' + (i + 1) + '</span><br/><br/>';
  }

  wrapper.innerHTML = myHTML

</script>

any help will be appreciated, and please dont just point out flaws and not tell me how to improve them.

isn't i < number ? Since you already specified that var i = 0. Also, instantiate the variable myHTML before the loop — Calvin Nunes
– Calvin Nunes, Commented Mar 5, 2020 at 12:27
You get an error in your script because you're using the undeclared variable myHTML — VLAZ
– VLAZ, Commented Mar 5, 2020 at 12:27
Also, as @CalvinNunes mentions, the exit condition for the loop is wrong - it will not terminate. — VLAZ
– VLAZ, Commented Mar 5, 2020 at 12:28
so how do i make it right? i have changed the i < number part — katekatekate
– katekatekate, Commented Mar 5, 2020 at 12:29

Mamun · Accepted Answer · 2020-03-05 12:47:39Z

2

You have two issues in your code. firstly, you have to declare the variable myHTML outside the loop with empty string. Secondly, in the loop i = number - 1 will prevent the iteration of the loop, try i < number

<div id="myHTMLWrapper">

</div>

<script>
  var wrapper = document.getElementById("myHTMLWrapper");

  var number = prompt("Enter the number of questions");
  var myHTML = '';
  for (var i = 0; i < number; i++) {
    myHTML += '<span class="test">Question ' + (i + 1) + '</span><br/><br/>';
  }

  wrapper.innerHTML = myHTML;

</script>

Though, here starting the loop iteration value from 1 with i <= number is more meaningful as this will allow you to use the value directly (without the increment) in the htmlString:

<div id="myHTMLWrapper">

</div>

<script>
  var wrapper = document.getElementById("myHTMLWrapper");

  var number = prompt("Enter the number of questions");
  var myHTML = '';
  for (var i = 1; i <= number; i++) {
    myHTML += '<span class="test">Question ' + i + '</span><br/><br/>';
  }

  wrapper.innerHTML = myHTML

</script>

edited Mar 5, 2020 at 12:47

answered Mar 5, 2020 at 12:30

Mamun

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1 Comment

katekatekate Over a year ago

thank you very much, i see now. im such a beginner in coding so i appreciate this a lot

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