GAS - Find empty cells rather slow - google-apps-script

Question

I have the following code in Google Apps Script. It loops through more than 800 rows to find empty cells of a column. But it takes too long. Is there a way to speed it up?
for(var t = 2; t <= lastrow; t++)
{
if (Geojson_Data.getRange(t,col1).getValue() == "")
{
Geojson_Data.deleteRow(t);
}
}

Answer 1

function delRowsWithNothingInColA() {
var ss=SpreadsheetApp.getActive();
var sh=ss.getActiveSheet();
var rg=sh.getRange(2,1,sh.getLastRow()-1,1);
var vA=rg.getValues();
var d=0;
for(var i=0;i<vA.length;i++) {
if(vA[i][0]=='') {
sh.deleteRow(i+2-d++)
}
}
}

Answer 2

var values = Geojson_Data.getDataRange().getValues();
var col1Arr = col1 - 1;
var t = values.length;
while(t--)
if(values[t][col1Arr] === '')
Geojson_Data.deleteRow(t + 1);
If you need a really tool then look at the snippet The script removes rows in batches without changing rows queue and without destroying formulas.
/**
* Runs the snippet.
* Removes rows by condition 'A:A=""'.
* #ignore
*/
function run() {
var sheet = SpreadsheetApp.getActiveSheet();
deleteRowsByConditional_(sheet, function(row) {
return row[0] === '';
});
}
function deleteRowsByConditional_(sheet, condition, action) {
var values = sheet.getDataRange().getValues();
values.unshift([]);
values.reverse().forEach(
function() {
var i = this.l - arguments[1];
if (this.condition.apply(null, [arguments[0], i, arguments[2]])) {
this.isContinue++;
} else if (this.isContinue) {
if (action) action(arguments[2], i, this.isContinue);
this.sheet.deleteRows(i, this.isContinue);
this.isContinue = 0;
}
},
{ sheet: sheet, condition: condition, isContinue: 0, l: values.length }
);
}