Changing row colour if value set?

Question

I'm trying to use the following script to change the row colour if a value in column N is set:

function onEdit() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName('Sheet1');
  var rows = sheet.getRange('n3:n700');
  var numRows = rows.getNumRows();
  var values = rows.getValues();

  for (var i = 0; i <= numRows - 1; i++) {
    for (var x in values[i]){
      if (values[i][x] == '4'){
        var n = i + 1;
        sheet.getRange('a'+n+':n'+n).setBackgroundColor('red');
      }
    }
  }
};

But unfortunately I get the following error message:

Cannot call method "getRange" of null.

I've also tried switching to the new spreadsheets and using conditional formatting with a formula if(n3 = "") with no joy, and to be honest even if that worked I'm not sure if there is an easy way to apply conditional formatting to each line.

Answer 1

In new Google Sheets if you select A3:Z20 and Format, Conditional formatting... and enter:

=$N3<>""  

for Custom formula is with a colour of your choice and Range: A3:Z20 then in the range A3:Z20 every cell should be coloured if the cell in Column N for the corresponding row is not empty.

Since such formatting is conditional the IF is not normally required.