Emanuele Feronato continues to update his great Drag and Match engine to Phaser 2.6.2. This time adding a feature to check for valid moves, and movement undo: "Today’s feature checks for valid matches after the player ends a move, performing an “undo” if the move did not make any match. In a Drag and Match engine, a valid match is made by three or more colors in a row, horizontally or vertically.
I borrowed some functions from my Bejeweled prototype to check for valid matches because there’s no need to reinvent the wheel."