Question

I was wondering if anyone could help me with getting this working.

I’m using HTML to create a table which has at least 1 row but no max number of rows – as they can be added/removed by the user – and 4 columns, 1st contains a checkbox and the last 2 contain drop down menus.

I wish to be able to store the values of those menus in an array only if that row’s checkbox has been checked. e.g if the first row has 1 and A as it’s dropdown values and the second row has 2 and B. If only row 1 has been checked the array should only contain [1,A]. Instead mine holds all the values including the non-checked ones i.e [1,A,2,B].

My code for Javascript function and html table are below:

function calculate(textID) {
  var table = document.getElementById('course'); //id of table
  var rowCount = table.rows.length;
  var array = []; //array to hold the values
  var c = 0;

  dmenus = document.getElementByTagName("select"); //get the drop down menus

  for (var a = 1; a < rowCount; i++) { //a = 1 as the 1st row contains column headings
    var row = table.rows[a];
    var check = row.cells[0].childNodes[0];
    if (null != check && true == check.checked) {
      for (var b = 0; b < dmenus.length; b++) {
        val = dmenus[b].options[dmenus[b].selectedIndex].value;
        array[c] = val; //set index of array to equal value of dropdown box
        c++;
      }
    } else {
      b++;
    }
  }
 

<table id="course">
  <tr>
    <td><input type="checkbox" name="ucheck" id="ucheck" onclick="checkAll('course')" /></td>
    <th style="color:white">Course Title</th>
    <th style="color:white">Credits</th>
    <th style="color:white">Grade</th>
  </tr>
  <tr>
    <td><input type="checkbox" name="tick" id="tick" /></td>
    <td><input type="text" /></td>
    <td>
      <select name="credits" id="credits">
                    <option...</select></td>
    <td>
      <select name="grade" id="grade">
                    <option...</td>
 </table>

It works only for the first row but if there are more than 1 row it doesn’t do what it’s supposed to. The coding platform I’m working on does not seem to support JQuery so Javascript code will be most appreciated.

Answer 1

Finally got it to work, rearranged the code a little bit. There’s probably a more efficient way of doing it, but hey it works for me 😀

var array = [];
var narray = [];
var a = 0;
var b = 0;
var c = 0;

ddownselects = document.getElementsByTagName("select");

//get all elements into one array
for (var j = 0; j < ddownselects.length; j++) {
  val = ddownselects[j].options[els[j].selectedIndex].value;
  array[a] = val;
  a++;
}

var rlen = array.length / 2; //number of rows
for (var i = 1; i <= rlen; i++) {
  var row = table.rows[i];
  var check = row.cells[0].childNodes[0];
  if (check.checked) {
    narray[b] = array[c]; //set array values to new array only if that row is checked
    b++;
    c++;
    narray[b] = array[c];
    b++;
    c++;
  } else {
    c += 2; //if not checked, got to next row's values
  }
 

<table id="course">
  <tr>
    <td><input type="checkbox" name="ucheck" id="ucheck" onclick="checkAll('course')" /></td>
    <th style="color:white">Course Title</th>
    <th style="color:white">Credits</th>
    <th style="color:white">Grade</th>
  </tr>
  <tr>
    <td><input type="checkbox" name="tick" id="tick" /></td>
    <td><input type="text" /></td>
    <td>
      <select name="credits" id="credits">
                    <option...</select></td>
    <td>
      <select name="grade" id="grade">
                    <option...</td>