如何使用javascript中的变量创建for循环？

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.

Answer 1

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>