#suggest {    background-color: #e0e0e0;    width: 200px;}

    var xhr;    function createXhr() {        if (window.XMLHttpRequest) {            xhr = new XMLHttpRequest();        } else {            xhr = new ActiveXObject("Microsoft.XMLHTTP");        }    }        /* 提示词被选中 */    function select(divElm){        var inputElm = document.getElementById("keyword");        // 选中提示词        inputElm.value=http://www.mamicode.com/divElm.innerText;        // 关闭提示框        document.getElementById("suggest").innerHTML="";    }    /* 输入后提示（输入1，有提示，否则没有） */    function search() {        var inputElm = document.getElementById("keyword");        // 获取输入的内容        var inputWord = inputElm.value;        createXhr();        xhr.onreadystatechange = function cbSearch() {            if (xhr.readyState == 4 && xhr.status == 200) {                var rsp = xhr.responseText;                var json = eval("(" + rsp + ")");                // 获取提示词组                var array = json.array;                var addHtml = "";                if (array!=null) {                    // 提示词组不为空，循环取词，添加div                    for ( var idx in array) {                        addHtml += "<div onclick=‘select(this)‘>" + array[idx] + "</div>";                    }                }                //提示框 设 提示词                document.getElementById("suggest").innerHTML = addHtml;            }        };        xhr.open("get", "AjaxServlet?para=" + inputWord, true);        xhr.send(null);    }

    <!-- 按键抬起才能取到输入内容，否则(keypress/keydown)是上次输入内容 -->    <input type="text" id="keyword" onkeyup="search()">    <br>    <div id="suggest"></div>

    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {            response.setCharacterEncoding("utf-8");            AhJson aj = new AhJson();            String para=request.getParameter("para");            JSONObject jo = new JSONObject();            JSONArray a = new JSONArray();            if ("1".equals(para)){                a.add("1");                a.add("163");                a.add("12306");                jo.put("array", a);            }            response.getWriter().write(jo.toString());    }