function countBGColor(range, ref) {

    var sheet = SpreadsheetApp.getActiveSheet();
    var color = sheet.getRange(ref).getBackground();
    var range = sheet.getRange(range);
    var rangeVal = range.getValues();
    var count = 0;
    var allColors = range.getBackgrounds();
    for (var i = 0; i < allColors.length; i++) {
        for (var j = 0; j < allColors[0].length; j++) {
            if (allColors[i][j] == color) count += 1;
        };
    };
    return count;
}

function Refresh() {

  var sheet = SpreadsheetApp.getActiveSheet();
  var range = sheet.getRange('D1');
  range.clear();
  SpreadsheetApp.flush();
 range.setFormula('=countBGColor("A1:A10","E1")');
}