js 获取dom 为null 测试

<!DOCTYPE html>
<html>
    <head>
    
    </head>
    <body>
        <h1> 这是H1 </h1>
        <div id="div1">

        </div>
        <script type="text/html" id="toolbar">
            <input type="text" class="larry-input" style="height:100%;" name="username" id="username" placeholder="按名称查询">
            <button class="layui-btn layui-btn-sm" lay-event="add" data-url="/Backstage/Person/Add">新增</button>
            <button class="layui-btn layui-btn-sm layui-btn-danger isDelete" id="pici" data-url="/Backstage/Person/BatchDel">批量删除</button>
        </script>
        
        <script type="text/javascript">
            var t  = document.getElementById("toolbar");
            var t_html = t.innerHTML;
            var t_text =t.innerText;
            var username = document.getElementById("username");//获取的是null
            var div = document.getElementById("div1");
            div.innerHTML = t_html; 
            div.innerHTML = t_text;
            username = document.getElementById("username");//获取的不为null
            var t1 =  0;
        </script>
    </body>
</html>
原文地址:https://www.cnblogs.com/enych/p/11504214.html