SumByColor v1.1 - Added methods for Foreground Color - replaced the deprecated getBackgroundColor() with getBackground()

subByColor.js

function getBackgroundColor(rangeSpecification) {
  var sheet = SpreadsheetApp.getActiveSpreadsheet();
  return sheet.getRange(rangeSpecification).getBackground();
}

function getForegroundColor(rangeSpecification) {
  var sheet = SpreadsheetApp.getActiveSpreadsheet();
  return sheet.getRange(rangeSpecification).getFontColor();
}


function sumWhereBackgroundColorIs(color, rangeSpecification) {
  var condition = function (cell) { return cell.getBackground() == color; };
  return sumByCondition(color, rangeSpecification, condition);
}

function sumWhereBackgroundColorIsNot(color, rangeSpecification) {
  var condition = function (cell) { return cell.getBackground() != color; };
  return sumByCondition(color, rangeSpecification, condition);
}

function sumWhereForegroundColorIs(color, rangeSpecification) {
  var condition = function (cell) { return cell.getFontColor() == color; };
  return sumByCondition(color, rangeSpecification, condition);
}

function sumWhereForegroundColorIsNot(color, rangeSpecification) {
  var condition = function (cell) { return cell.getFontColor() != color; };
  return sumByCondition(color, rangeSpecification, condition);
}




function sumByCondition(color, rangeSpecification, condition) {
  var sheet = SpreadsheetApp.getActiveSpreadsheet();
  var range = sheet.getRange(rangeSpecification);
  
  var x = 0;
  
  for (var i = 1; i <= range.getNumRows(); i++) {
    for (var j = 1; j <= range.getNumColumns(); j++) {
      
      var cell = range.getCell(i, j);
      
      if(condition(cell))
        x += parseFloat(cell.getValue());
    }
  }
  
  return x;
}

Added skip empty cells in this fork: https://gist.github.com/jeffdgr8/1553faa6360ad04e9c17

If you want to do multiple lines filtered by color you can use this instead of "A1:A2" types of strings which you cannot drag in spreadsheets:

=getBackgroundColor(CONCAT("G", ROW(G2))) for a column, vice versa for a row

Thank you all!
I combined WaffleSouffle's work and jeffdgr8.
Everything is here in this fork: https://gist.github.com/jwdinkel/6e4051f057d62204907b

Anybody know how to cause the functions to update if the color of a cell in the range is changed?