求助 mui-tab-item onclick 事件真机无响应

代码如下，我是想通过触发 来显示当前页面，隐藏其他页面

<nav class="mui-bar mui-bar-tab nav-bgcolor">  
        <a class="mui-tab-item mui-active" id="square.html">  
            <span class="mui-icon mui-icon-navigate"></span>  
            <span class="mui-tab-label">广场</span>  
        </a>  
        <a class="mui-tab-item" id="message.html">  
            <span class="mui-icon mui-icon-chatboxes"></span>  
            <span class="mui-tab-label">信息</span>  
        </a>  
        <a class="mui-tab-item" id="mine.html">  
            <span class="mui-icon mui-icon-contact"></span>  
            <span class="mui-tab-label">我的</span>  
        </a>  
    </nav>  
    <script type="text/javascript">  
        var main = null, webView = null;  
        var square_index = null, message_index = null, mine_html = null;  
        var navList = document.getElementsByClassName('mui-tab-item');  
        var navJson = {};  
        var mainStyle = {top:'45px', bottom:'45px'};  

        if(window.plus){  
            plusReady();  
        }else{  
            document.addEventListener("plusready",plusReady,false);  
        }  // if finish;  

        function plusReady(){  
            main = plus.webview.currentWebview();  
            for(var i=0,n=navList.length;i<n;i++){  
                var id_ = navList[i].getAttribute('id');  
                console.log(id_)  
                navJson[id_] = plus.webview.create(id_, id_, mainStyle);  
            };  
            navJson['square.html'].show();  

        };  // function finish;  

        for(var i=0,n=navList.length;i<n;i++){  
            navList[i].onclick = function(){  
                alert(this.getAttribute('id'))  
            };  
        };