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JavaScript

Posted by Tani Huang
Tani Huang
6,952 Points

What is the difference between these two function ? (for loop)

//This is the correct answer
function listitem(arr) {
  listHTML = "<ul>";
    for (var i = 0 ; i < arr.length ; i += 1) {
    listHTML += "<li>" + arr[i] + "</li>";
  };
  listHTML += "</ul>";
  return listHTML;
};

//Eddit by myself
function listitem(arr) {
  for (var i = 0 ; i < arr.length ; i += 1) {
    listLi = "<li>" + arr[i] + "</li>";
  };
  listUl = "<ul>" + listLi + "</ul>";
  return listUl;
};

1 Answer

Heidi Puk Hermann
Heidi Puk Hermann
33,366 Points
Heidi Puk Hermann
Heidi Puk Hermann
33,366 Points

Hi Tani,

In the first snippet you are appending an additional li element to the ul every time the for-loop has complete a step. If you ran it three times you would get the following:

  1. time: listHTML = "<ul>" + "<li>" + arr[0] + "</li>"

  2. time listHTML = "<ul>" + "<li>" + arr[0] + "</li>" + "<li>" + arr[1] + "</li>"

  3. time listHTML = "<ul>" + "<li>" + arr[0] + "</li>" + "<li>" + arr[1] + "</li>" + "<li>" + arr[2] + "</li>"

In the second snippet you are re-setting the value of your string, listLi every time you run the loop. The output would look like this, if you ran the loop three times:

  1. time listLi = listLi = "<li>" + arr[0] + "</li>"

  2. time listLi = "<li>" + arr[1] + "</li>"

  3. time listLi = "<li>" + arr[2] + "</li>"

In the end it comes down to wether you put += (append) or = (set) after the name of your variable.

Tani Huang
Tani Huang
6,952 Points

Thank you Heidi