Sum rows in javascript (not a table)

Question

I have an textarea for input of values that are rows and columns (but not a table) and I want to be able to add the values of the rows individually. My logic is that I get the user to input the number of rows they have entered, split the input to make a string and then split it up by the number of rows they input. Hereis what I have. Happy for better solutions. Alternately I did some reading and thought I could convert the rows to actual <tr>s and then go through them (I would also like to be able to this for columns at a later stage). Thanks in advance:

<html>
<head>
<script type='text/javascript'>

function sum(){ 
var rows= document.getElementById('rows').value;
    var val = document.getElementById('userInput').value;
    var temp = val.split(" ");
var lines=temp.split(rows);

var total = 0;
var v;

    for(var i = 0; i < temp.length; i++) {
      v = parseFloat(lines[i]);
      //this is what I am missing to get each row's sum separately
    } 




document.write(//each row total); 


  } 

</script>
</head>
<body>
<form id="input">
  <textarea id="userInput"></textarea> 
Number of rows: <textarea id="rows"></textarea>
  <input id="Run" type=Button value="run" onClick="sum()" />
</form>


</body>
</html>

So now I have the following (I had to add v back in) but it is returning NaN (and noting I will address the final suggestion anyway):

<script type='text/javascript'>
 function sum() {
var grandTotal = 0,
   rowTotals = [], // array to hold individual row totals
   rowData,
   rows,
   val,
var v;
   rawData = document.getElementById('userInput').value;


 rows = rawData.split("\n");

 for (var i=0; i < rows.length; i++) {
  rowTotals[i] = 0;
  rowData = rows[i].split(" ");

  for (var j=0; j < rowData.length; j++) {
     val = parseFloat(rowData[j]);
    if (!isNaN(v)) rowTotals[i] += v;
  }
  alert("Total for row " + (i + 1) + ": " + rowTotals[i]);
  grandTotal += rowTotals[i];
 }

 alert("Grand total: " + grandTotal);
}


</script>

Why do you need the user to tell you how many rows they've entered? Can't you just split the entered string on \n or \r or something and then get the length of the resulting array to tell you how many rows there are? Also, presumably the user has entered a number for "Number of rows:", so I don't understand why you would use that number as the parameter passed to .split(rows). — nnnnnn
– nnnnnn, Commented Sep 9, 2011 at 2:58
OK, that makes sense, my question remains though, how do I then get the sum for each row independently? thanks. — tc03
– tc03, Commented Sep 9, 2011 at 3:56

nnnnnn · Accepted Answer · 2011-09-09 06:19:02Z

Assuming the user has entered data in this format:

12.1 4.8 11.2 4.1
1.2 3.4 5.6 99.9
etc

That is, with a new line at the end of each row and spaces between the numbers, then you could do something like this:

function sum() {
   var grandTotal = 0,
       rowTotals = [], // array to hold individual row totals
       rowData,
       rows,
       val,
       rawData = document.getElementById('userInput').value;

   // if desired replace this comment with regex validation of rawData

   rows = rawData.split("\n");

   for (var i=0; i < rows.length; i++) {
      rowTotals[i] = 0;
      rowData = rows[i].split(" ");
      // if you need to test that each row has the same number
      // of values in it do that here

      for (var j=0; j < rowData.length; j++) {
         val = parseFloat(rowData[j]);
         // add validation of val here
         rowTotals[i] += val;
      }
      alert("Total for row " + (i + 1) + ": " + rowTotals[i]);
      grandTotal += rowTotals[i];
   }

   // at this point rowTotals is an array containing
   // the individual row totals, so do what you like with that

   alert("Grand total: " + grandTotal);
}

There are two points in the function where you will need to do some more work:

You must check that the result from parseFloat() is actually a number - the user may have entered alphabetic characters or punctuation, in which case it'll return NaN. Alternatively use a regular expression to validate the whole string for formatting and illegal characters before you do anything else.
Splitting the string on newline "\n" can be a problem in that different platforms use different characters for line breaks. I believe some use just newline "\n", some use just carriage return "\r" and some use both. You could probably normalise that before the split using a find-and-replace.

I leave both points as an exercise for the reader...

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