change keyboard layout with javascript

You won’t be able to change the keyboard layout using JS, but you can capture the keydown event and replace the character with something like this:

http://jsfiddle.net/SxdKZ/

$('textarea').on('keydown', function(e){

   console.log(e.keyCode); 
    if( e.keyCode == 90 ){
      e.preventDefault();
      $(this).append('y').focus();
    }
    if( e.keyCode == 89 ){
      e.preventDefault();
      $(this).append('z').focus();
    }

});​