JS如何获取iframe内html的body值

default页面：

<html>
<head>
    <script type="text/javascript">
        window.onload=function()
        {
            var img = document.frames["IFeditValue"].document.getElementById('editValue');
            alert(img.innerHTML);
        }
    </script>
</head>
<body>
    <iframe id="IFeditValue" src="blank.html"  scrolling="auto" height="800" width="1000"></iframe>
</body>
</html>

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