Google Sheets Script to Fill Down intermittent blanks in a column - google-apps-script

Question

Column C has an ID in it that pertains to several rows, but only the first row has an ID in it.
I need to copy that ID value to the blank cells beneath, until I hit a cell that has another value in it.
I have tried adapting this script but it hits a timeout error.
function myFunction() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
var last = sheet.getLastRow();//how many times should I do this?
for (i = 5528; i < last; i++) {
var test = sheet.getRange(i, 1,1,1);
//Logger.log(test);
//looks to see if the cell is empty
if (test.isBlank()) {
var rewind = sheet.getRange(i-1, 1, 1, 1).getValues();//gets values from the row above
sheet.getRange(i, 1, 1, 1).setValues(rewind);//sets the current range to the row above
}
}
}
i is set to a big number because every time it times out I have to start over!
I have read that it would be better to bring in the column in an array, work on it, then put it back out to save a lot of time.
I have tried to adapt this but can't get past the variable.
Am I on the right track? I would like to pretty up a solution for the future where I can pass a column or range and do the same thing.
Here is my failing attempt:
function FillDown2() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getSheetByName("Sheet2");
var tracts = sheet.getRange("C15:C").getValues();
var allTractList = [];
var title;
for (var row = 0, var len = tracts.length; row < len; row++) {
if (tracts[row][0] != '') {
//response = UrlFetchApp.fetch(tracts[row]);
//doc = Xml.parse(response.getContentText(),true);
title = tracts[row][0];
//newValues.push([title]);
allTractList.push([title]);
Logger.log(title);
} else allTractList.push([title]);
}
//Logger.log('newValues ' + newValues);
Logger.log('allTractList ' + allTractList);
// SET NEW COLUMN VALUES ALL AT ONCE!
sheet.getRange("B15").offset(0, 0, allTractList.length).setValues(allTractList);
return allTractList;
}

Answer 1

Holy Smokes! I did it!
Not sure about why error happened but I had made some changes and got it to work!
Hope this is helpful to others:
function FillDown2() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getSheetByName("Sheet2");
var tracts = sheet.getRange("C15:C").getValues();
var allTractList = [];
var title;
var len = tracts.length;
for (var row = 0; row < len; row++) {
if (tracts[row] != '') {
//response = UrlFetchApp.fetch(tracts[row]);
//doc = Xml.parse(response.getContentText(),true);
title = tracts[row];
//newValues.push([title]);
allTractList.push([title]);
Logger.log(title);
} else allTractList.push([title]);
}
//Logger.log('newValues ' + newValues);
Logger.log('allTractList ' + allTractList);
// SET NEW COLUMN VALUES ALL AT ONCE!
sheet.getRange("B15").offset(0, 0, allTractList.length).setValues(allTractList);
return allTractList;
}
Credit to Bryan here: