试图，点击按钮，插入新节点，这里的代码错在哪里？

<html>
<head>
<script type="text/javascript">
var idcount = 0;

function insert(){
alert("oo");
var obj = getElementById("input0");
alert("xx");
var newNode = createNewNode("hhhhhhhh");
obj.parentNode.insertBefore(newNode, obj);
}

function createNewNode( text ){
var newNode = document.createElement( "p" );
var nodeId = "new" + idcount;
++idcount;
newNode.id = nodeId;
text = "[" + nodeId + "] " + text;
newNode.appendChild(document.createTextNode( text ) );
return newNode;
}
</script>
</head>
<body>
<input id="input0" type="text" value="xxxxx" />
<input id="button0" type="button" value="insert" onclick="insert()" />
</body>
</html>

解决方案 »

免费领取超大流量手机卡，每月29元包185G流量+100分钟通话, 中国电信官方发货

<html>
    <head>
        <script type="text/javascript">
            var idcount = 0;

            function insert(){
                alert("oo");
                var obj = document.getElementById("input0");
                alert("xx");
                var newNode = createNewNode("hhhhhhhh");
                obj.parentNode.insertBefore(newNode, obj);
            }

            function createNewNode( text ){
                var newNode = document.createElement( "p" );
                var nodeId = "new" + idcount;
                ++idcount;
                newNode.id = nodeId;
                text = "[" + nodeId + "] " + text;
                newNode.appendChild(document.createTextNode( text ) );
                return newNode;
            }
        </script>
    </head>
    <body>
        <input id="input0"  type="text"   value="xxxxx" />
        <input id="button0" type="button" value="insert" onclick="insert()" />
    </body>
</html>
使用函数的时候，window对象可以省略
如 window.alert("x")可以写为 alert("x")，因为window代码浏览器窗口，而函数执行的默认对象就是window
但document.getElemenyById("x")的document就不能省略了