Javascript not incrementing a variable

Question

I would like to keep count every time the user clicks a the add row button. Here's the code I have that's not working.

function add_more_row() {
  var rows_count = ParseInt(document.getElementById("rows_count").value);
  rows_count += 1;
}

<input type="text" value="0" id="rows_count" />
<input onclick="add_more_row();" type="button" value="add row" />

What am I doing wrong?

Just so you know, the statement that you've read previous/related questions isn't helpful if you don't link to what questions you're referring to and describe why they didn't help. — castletheperson
– castletheperson, Commented Nov 10, 2016 at 2:24

Nhan · Accepted Answer · 2016-11-10 06:39:03Z

2

Your code only gets the value and increases it, does not assign the value to the input field. Add this line after the increment statement:

document.getElementById("rows_count").value = rows_count;

Also it's parseInt() with lowercase p not ParseInt().

function add_more_row() {
  var inputRow = document.getElementById("rows_count"),
      rows_count = parseInt(inputRow.value);
  rows_count += 1;
  inputRow.value = rows_count;
}

<input type="text" value="0" id="rows_count" />
<input onclick="add_more_row();" type="button" value="add row" />

edited Nov 10, 2016 at 6:39

answered Nov 10, 2016 at 2:24

Nhan

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1 Comment

user663031 Over a year ago

Retrieving the element from the DOM twice is sloppy.

Redhya · Accepted Answer · 2016-11-10 05:32:59Z

1

function add_more_row() {
  var rows_count = parseInt(document.getElementById("rows_count").value);
  rows_count += 1;
  document.getElementById("rows_count").value= rows_count;
}

<input type="text" value="0" id="rows_count" />
<input onclick="add_more_row();" type="button" value="add row" />

answered Nov 10, 2016 at 5:32

Redhya

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Comments

The KNVB · Accepted Answer · 2016-11-10 02:24:06Z

0

It is because you declare the variable inside the function. So, the variable does not increase.

 var rows_count=ParseInt(document.getElementById("rows_count").value);
 function add_more_row()
 {
   rows_count += 1;
 }

answered Nov 10, 2016 at 2:24

The KNVB

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2 Comments

the7k Over a year ago

Nope, I only need that variable inside the function scope. Thank you though.

user663031 Over a year ago

Unfortunately, this won't work. And you haven't fixed the typo with ParseInt.

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