jquery如何判断是否按下了Enter键

$('#textBox').keypress(function(event){ 

    var keynum = (event.keyCode ? event.keyCode : event.which); 

    if(keynum == '13'){ 

        alert('You pressed a "Enter" key in textbox');   

    } 

}); 

$(document).keypress(function(event){ 

    var keynum = (event.keyCode ? event.keyCode : event.which); 

    if(keynum == '13'){ 

        alert('You pressed a "Enter" key in somewhere');     

    } 

});