via：http://shikargar.wordpress.com/2010/10/27/javascript-key-codes/
在页面上增加键盘快捷键：
var inputFocus = false;
$(':input').blur(function(){
inputFocus = false;
});
$(':input').focus(function(){
inputFocus = true;
});
$(document).keydown(function(e){
if(!inputFocus){
if(e.which == 87 && !e.ctrlKey){
//do something
return false;
}
}
});
