JQuery判断页面是否按下了Enter键

$('#someTextBox').keypress(function(event){  
 
    var keycode = (event.keyCode ? event.keyCode : event.which);  
 
if(keycode == '13'){  
 
        alert('You pressed a "enter" key in textbox');    
 
    }  
 
});  
 
$(document).keypress(function(event){  
 
    var keycode = (event.keyCode ? event.keyCode : event.which);  
 
if(keycode == '13'){  
 
        alert('You pressed a "enter" key in somewhere');      
 
    }  
 
});