回车键搜索兼容性问题
document.onkeydown = keyDownSearch;
function keyDownSearch(e) { // 兼容FF和IE和Opera
var theEvent = e || window.event;
var code = theEvent.keyCode || theEvent.which || theEvent.charCode;
if (code == 13) { return false; } return true; }
原文：http://www.cnblogs.com/earnest/p/6607305.html