Simply put, the guy simply named Grant Galitz used JavaScript to write an open source GameBoy Color emulator screen display by HTML5. And he also provided the American version of the legend of Zelda: DX DX (the Legend Of Zelda:Link ' s Awakening DX) address online game:

Hit here to play the game resolution Adaptive browser window, so it is best to play in a new window. Default action is key to key, Enter (Start) and Shift (Select), x (a) and z (b). (Archives for four key press) using Firefox 5 to get the best results. If your computer has a GBC Rom of the game, you can also open local files in the emulator and play in the browser--of course, have said there is no mystery. And if people recommend, may wish to completely conceal information about the emulator up directly to the Web site of Zelda him!