Html cross domain policy造成的iframe自适应高度的解决办法

今天android加载html的时候遇到无法滚动显示完整内容的问题，确认没有disable scroll方法，经查证是属于iframe设置高度造成的，加载外部html的时候，因为安全策略无法访问到iframe的contentDocument，造成高度不正确。报错：Uncaught SecurityError: Failed to read the 'contentDocument' property from 'HTMLIFrameElement': Blocked a frame with originnull from accessing a frame with origi null

chrome 会限制protocol，cross domain等等，我遇到的就是local html file 的路径问题，虽然是同一个文件夹里的内容。

解决方法就是postmessage，利用event来通信传递自身的高度过去。

这里通配了domain，注意安全性的话，需要post domain and check it at message handler.

parent :

<script type="text/javascript">
    // browser compatibility: get method for event 
    // addEventListener(FF, Webkit, Opera, IE9+) and attachEvent(IE5-8)
    var myEventMethod = 
        window.addEventListener ? "addEventListener" : "attachEvent";
    // create event listener
    var myEventListener = window[myEventMethod];
    // browser compatibility: attach event uses onmessage
    var myEventMessage = 
        myEventMethod == "attachEvent" ? "onmessage" : "message";
    // register callback function on incoming message
    myEventListener(myEventMessage, function (e) {
        // we will get a string (better browser support) and validate
        // if it is an int - set the height of the iframe #my-iframe-id
        if (e.data === parseInt(e.data)) 
            document.getElementById('my-iframe-id').height = e.data + "px";
    }, false);
</script>

child

<script type="text/javascript">
    // all content including images has been loaded
    window.onload = function() {
        // post our message to the parent
        window.parent.postMessage(
            // get height of the content
            document.body.scrollHeight
            // set target domain
            ,"*"
        )
    };
</script>