Google sheets, get range of rows, where column intersect cell is empty - sorting

Question

Basically I want to use an auto-sorting script through the script editor in Google sheets, but I want it to smartly pick a range of rows, by only selecting those rows where a specific column has an empty cell.
All other rows that have that column's cell populated would stay put. Here is the sort code I've found.
/**
* Automatically sorts the 1st column (not the header row) Ascending.
*/
function onEdit(event){
var sheet = event.source.getActiveSheet();
var editedCell = sheet.getActiveCell();
var columnToSortBy = 1;
var tableRange = "A2:T99"; // What to sort.
if(editedCell.getColumn() == columnToSortBy){
var range = sheet.getRange(tableRange);
range.sort( { column : columnToSortBy, ascending: true } );
}
}
Thanks.

Answer 1

Note: this will only sort the values in the cells (metadata such as formats, notes etc will not be sorted, as they would with the GAS range.sort() method).
function onEdit(event)
{
var sheet = event.source.getActiveSheet();
var editedCell = sheet.getActiveCell();
var columnToSortBy = 0; // zero-based index
if (editedCell.getColumn() == columnToSortBy)
{
var columnToWatch = 5; // checking this column for blank cells (zero-based index)
var tableRange = "A2:T99"; // what to sort
var range = sheet.getRange(tableRange);
var data = range.getValues();
var dataCopy = data.slice();
dataCopy.sort(function(a, b) {return a[columnToSortBy] > b[columnToSortBy] ? 1 : (a[columnToSortBy] < b[columnToSortBy] ? -1 : 0);});
var j = -1;
for (var i = 0, length = data.length; i < length; i++)
{
if (data[i][columnToWatch].toString().length)
{
do j++; while (!dataCopy[j][columnToWatch].toString().length);
data[i] = dataCopy[j];
}
}
range.setValues(data);
}
}