Google Docs Script that gives the sum of values in cells of a sheet that match with a specified background colour

sumMatchingColoredCells.gs

/**
* @param {range} sumRange Range to be evaluated
* @param {range} colorRef Cell with background color to be searched for in sumRange
* @return {number}
* @customfunction
*/

function sumMatchingColoredCells(sumRange,colorRef) {
  var activeRange = SpreadsheetApp.getActiveRange();
  var activeSheet = activeRange.getSheet();
  var formula = activeRange.getFormula().toString();
  formula = formula.replace(new RegExp(';','g'),',');
  
  
  var rangeA1Notation = formula.match(/\((.*)\,/).pop();
  var range = activeSheet.getRange(rangeA1Notation);
  var bg = range.getBackgrounds();
  var values = range.getValues();
  
  var colorCellA1Notation = formula.match(/\,(.*)\)/).pop();
  var colorCell = activeSheet.getRange(colorCellA1Notation);
  var color = colorCell.getBackground();
  
  var total = 0;
  
  for(var i=0;i<bg.length;i++)
    for(var j=0;j<bg[0].length;j++)
      if( bg[i][j] == color )
        total=total+(values[i][j]*1);
  return total;
};