How to loop properly

Question

So here is the overall of what I need to do

Start with confirming if the user wants to add a course, if they click ok it gives them a prompt to enter course if they hit cancel it finishes the program.
When the user gives an answer to the course, they then need to give their grade for that specific course.
Once those two questions are done it needs to go back to ask them if they want to add a course again

this is what i have so far

while (true) {
  var entering = confirm('Do you want to enter a Course?');
  if (entering = true) {
    break;
  }

}
var codeInput = '';
var gradeInput = '';
while (true) {
  codeInput = prompt('Enter Course Code');
  if (codeInput.length === 7) {
    break;
  }
  alert('invalid code');
}

gradeInput = prompt('Enter Grade for ' + codeInput + '');


document.writeln('<table border="1">');
document.writeln('<tr>');
document.writeln('<th>Course Code</th>');
document.writeln('<th>Grade</th>');
document.writeln('<tr>');
document.writeln('<th>' +
  codeInput +
  '</th>');
document.writeln('<th>' +
  gradeInput +
  '</th>');
document.writeln('</tr>');

So I'm not sure how to loop it back to the start and how to make the program stop when you hit cancel when it asks if you want to add another course. I also do not know how to make it so if the user asks to enter another course/grade how to make them into a separate answer to add below in the table.

I hope this makes sense and if anyone can help would be lovely thank you!

ps. This has to all be done using javascript no HTML.

You can use recursion here rather than putting em in while loop — Lokesh Pandey
– Lokesh Pandey, Commented Sep 11, 2018 at 11:36
I haven't learnt recursions yet so I need to use while loops or any kind of loop that will work — Sully
– Sully, Commented Sep 11, 2018 at 11:42

Zakaria Acharki · Accepted Answer · 2018-09-11 13:57:22Z

1

Working fiddle.

Wrap your code in a function so you could call it every time you enter the grad to ask it again.

I suggest to create the table and the header then append the rows when the user answers the prompts :

var number_of_rows = 0;
var table = document.createElement('table');
table.border = '1';

ask();

function ask() {
  var codeInput = '';
  var gradeInput = '';

  var entering = confirm('Do you want to enter a Course?');

  if (!entering) {
    return;
  } else {
    while (true) {
      codeInput = prompt('Enter Course Code');

      if (codeInput.length === 7) {
        break;
      }

      alert('invalid code');
    }
  }

  gradeInput = prompt('Enter Grade for ' + codeInput + '');

  if (number_of_rows === 0) {
    var row = document.createElement('tr');
    var th_1 = document.createElement('th');
    var th_2 = document.createElement('th');
    var txt_1 = document.createTextNode("Course Code");
    var txt_2 = document.createTextNode("Grade");
    th_1.appendChild(txt_1);
    th_2.appendChild(txt_2);
    row.appendChild(th_1);
    row.appendChild(th_2);
    table.appendChild(row);

    number_of_rows++;
  }


  console.log(number_of_rows);

  table = insertRow(codeInput, gradeInput);

  document.body.appendChild(table);
  number_of_rows++;

  ask();
}

function insertRow(codeInput, gradeInput) {
  var row = document.createElement('tr');
  var td_1 = document.createElement('td');
  var td_2 = document.createElement('td');
  var txt_1 = document.createTextNode(codeInput);
  var txt_2 = document.createTextNode(gradeInput);

  td_1.appendChild(txt_1);
  td_2.appendChild(txt_2);
  row.appendChild(td_1);
  row.appendChild(td_2);

  table.appendChild(row);

  return table;
}

edited Sep 11, 2018 at 13:57

answered Sep 11, 2018 at 11:47

Zakaria Acharki

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4 Comments

Sully Over a year ago

Thank you so much for your help I do appreciate it, but one thing i forgot to mention in my question was that it has to be done in all of javascript no html.

Sully Over a year ago

for some reason it runs on here but when I put it in my text editor and open it in firefox it starts fine but when I enter in the grade for the course instead of asking if i want to enter another one that doesn't pop up and I cant do anything and the table doesn't show up. i look at the console of firefox and it told me this "document.body is null" which is for the line "document.body.appendChild(table);" so not sure what this means.

Sully Over a year ago

I think i fixed it i used "window.onload = function()" before the first ask() and it seems to work. Thank you so much, you have been a big help!

Zakaria Acharki Over a year ago

Good job, glad I could helps. HAPPY CODING.

Chris Li · Accepted Answer · 2018-09-11 11:39:43Z

0

According to here https://developer.mozilla.org/en-US/docs/Web/API/Window/prompt

If the user clicks the Cancel button, this function returns null

So all you need is to check if value is null to know if the user clicked cancel

if (codeInput == null) break

answered Sep 11, 2018 at 11:39

Chris Li

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