js 判断是否为数字

if (data.value === "" || data.value == null) {
                return false;
            }
            console.log(!isNaN(data.value)); // 1 输出true ;   // isNaN(data.value) = false,  是数字返回false ,

            var value = document.getElementById("jmp").value;
            value = value.replace(/\ /g, "");
            if (value === "") {
                return;
            }
            var t = isNaN(value);
            if (t) {
                alert("请输入要跳转的页数");
                return;
            }
            fun_call(indexpage);

---

 var Jmp = document.getElementById("pagejump");
        Jmp.onclick = function () {
            var index = document.getElementById("tzxzk").value;
            index = parseInt(index);
            if (index.toString() == "NaN") {
                alert("请输入要跳转的页数");
                return;
            }
            if (isNaN(index)) {
                alert("请输入要跳转的页数！");
                return;
            }
            Check_page(index) && post_test(index);
        }

---

end

---

begin

    <div class="page_btn clearfix">
                <span id="total" class="zg_page">共42条</span>
                <span id="currentpage" class="zg_page">第1页</span>
                <span id="pagesize" class="zg_page">共3页</span>
                <a href="javascript:;" id="firstpage">首　页</a>
                <a href="javascript:;" id="prepage">上一页</a>
                <a href="javascript:;" id="nextpage">下一页</a>
                <a href="javascript:;" id="lastpage">尾　页</a>
                <div class="tz">
                    <span>到第</span>
                    <input name="gotopage" type="text" id="tzxzk" class="xzk">
                    <span>页</span>
                    <input id="pagejump" value="确定" class="sure">
                </div>
            </div>
------------------------

<script>
        var pageindex = 0;
        var pages = 0;
        var first = document.getElementById("firstpage");
        var Up = document.getElementById("prepage");
        var Down = document.getElementById("nextpage");
        var End = document.getElementById("lastpage");
        var Jmp = document.getElementById("pagejump");
        Jmp.onclick = function () {
            var index = document.getElementById("tzxzk").value;
            index = parseInt(index);
            if (isNaN(index)) {
                alert("请输入要跳转的页数！");
                return;
            }
            Check_page(index) && post_test(index);
        }
        //检测要跳转的页数
        function Check_page(index, type) {
            var message = "输出的页数超出范围!";
            if (index < 1) {
                if (type) {
                    message = "已经是第一页数据!";
                }
                alert(message);
                return false;
            }else
                if (index > pages) {
                    if (type) {
                        message = "已经是最后一页数据!";
                    }
                    alert(message);
                    return false;
                }
            return true;
        }
        first.onclick = function () {
            post_test(1);
        }
        End.onclick = function () {
            var max_index = pages;

            post_test(max_index);
        }
        Up.onclick = function () {
            //获得当前页
            //当前页-1
            var index = pageindex - 1;
            Check_page(index,1) && post_test(index);
        }
        Down.onclick = function () {
            //获得当前页
            //当前页+ 1
            var index = pageindex + 1;
            Check_page(index,1) && post_test(index);
        }

        function page_count(count, index) {
            //共多少条//共多少页
            document.getElementById("total").innerHTML = "共" + count + "条";
            pages = Math.ceil(parseInt(count) / 15);
            document.getElementById("currentpage").innerHTML = "第" + index + "页";
            document.getElementById("pagesize").innerHTML = "共" + pages + "页";
        }

    </script>

    <script>

        //function (url,type,data,callback)
        var isclick = true;
        function post_test(index) {
            //当前页
            pageindex = index;

            if (isclick) {
                isclick = false;
                //---
                var posturl = "/Navig/Get_MatterList";
                var formData = new FormData();
                formData.append("id", document.getElementById("type_id").value);
                formData.append("index", index);
                myxhr.mypost(posturl, 'json', formData,
                    function (data) {
                        var that = data.data;

                        page_count(data.count, index);

                        var sb = new StringBuilder();
                        for (var i = 0; i < that.length; i++) {
                            var t;
                            //if (that[i]._WH.indexOf("|") >= 0) {
                            //    t = that[i]._WH.split("|");
                            //    for (var j = 0; j < t.length; j++) {
                            //        if (t[j].indexOf('%') == -1) {
                            //            t[j] = t[j] + "px";
                            //        }
                            //    }
                            //} else {
                            //    t.push("500px");
                            //    t.push("400px");
                            //}
                            //that[i].HFEventName
                            //that[i]._Ico

                            sb.appendFormat(' <li style="margin-top: 40px;"><a href="javascript:;" class="link"><div class="icon-box"><img style="width:100%;" src="{0}" alt=""></div><p class="link-title">{1}</p></a></li>',
                                that[i]._Ico,
                                that[i].HFEventName
                            );
                        }
                        var result = sb.toString();
                        var ul = document.getElementById("itemlist");
                        ul.innerHTML = result;

                        var lis = ul.getElementsByTagName("li");
                        for (var i = 0; i < lis.length; i++) {
                            lis[i].onclick = function () {
                                //alert(this.getAttribute("data_url"));
                                //window.location = (this.getAttribute("data_url") + "/?id=" + this.getAttribute("data_id"));
                            }
                        }

                    });
                //---
                setTimeout(function () {
                    isclick = true;
                }, 500);
            }
        }
        window.onload = function () {
            post_test(1);
        }
    </script>