我有这段有效的代码:functiondoStuff1(){vareml=document.getElementsByName('email')[0].value;msg=document.getElementsByName('message')[0];msg.value=eml+''+msg.value;alert('Messagehasbeensubmitted');returntrue;//returnfalsetotestjustmessageboxandupdatedmessagetextarea}但是，当我使用getElementById而不是getElementsByNam