First and foremost. Never ever use l
(lower case el) as a variable. It is far to similar to 1
(one). Also be careful with upper case "o", and upper-case "i". Lowercase "o" is also often disliked.
It might look OK now, but when you review it in 6 months or a year, perhaps not so much. Also consider others might have to both read and modify your code.
Enough about that.
Your code, as it is, should work. If you do not get the desired result then the problem is elsewhere.
Make it reusable
However, to simplify the code and make it easier to re-use, you can add a parameter for id of the table as well as desired column. Resulting function could be something like this, with some extra checks:
function getColumn(table_id, col) {
var tab = document.getElementById(table_id);
var n = tab.rows.length;
var i, s = null, tr, td;
// First check that col is not less then 0
if (col < 0) {
return null;
}
for (i = 0; i < n; i++) {
tr = tab.rows[i];
if (tr.cells.length > col) { // Check that cell exists before you try
td = tr.cells[col]; // to access it.
s += ' ' + td.innerText;
} // Here you could say else { return null; } if you want it to fail
// when requested column is out of bounds. It depends.
}
return s;
}
var txt = getColumn('partTable', 2);
Check for failure
By using null
as initial value for s
, we can compare returned result with null
to see if it was successful.
if (txt === null) {
// Report error, or at least not work on "txt".
}
Simplify
Once you really understand it you can, if you want, simplify the loop to something like this:
for (i = 0; i < n; i++) {
if (tab.rows[i].cells.length > col) {
s += ' ' + tab.rows[i].cells[col].innerText;
}
}
Use Array:
If you are going to use the cells one by one the best approach would be to return an Array instead of a string. Then you can loop the array, or if you want it as a string simply join it with desired delimiter. This would most likely be the most useful and reusable function.
// In function:
arr = [];
// In loop:
arr.push(tab.rows[i].cells[col].innerText);
var cells = getColumn("the_id", 2);
var text = cells.join(' ');
Demo:
Speed.
If your table cells does not contain any <script>
or <style>
, which they should not, you can also consider using textContent
over innerText
. Especially if table is large. It is a much faster. Here is a short article on the subject from Kelly Norton: