Hi, I’m Adam Lu.

跨域Iframe高度自适应

在CSS Trick上面看到了一篇讲跨域Iframe调整的文章，DEMO在这里。要做到跨域Iframe高度自适应，需要可以控制两个域内的内容，主要的技术是通window.location.hash来传递信息。

先来看看主域的内容：

<iframe id="frame-one" scrolling="no" frameborder="0" src="http://digwp.com/examples/iFrameSource/source.html"
 onload="FrameManager.registerFrame(this)"></iframe>
放置一个需要高度自适应的Iframe，onload时会调用一个函数，这个函数在下面的这个js里面
<script type="text/javascript" src="js/FrameManager.js"></script>，这个js的内容如下：
var FrameManager = {
    currentFrameId : '',
    currentFrameHeight : 0,
    lastFrameId : '',
    lastFrameHeight : 0,
    resizeTimerId : null,
    init: function() {
        if (FrameManager.resizeTimerId == null) {
            FrameManager.resizeTimerId = window.setInterval(FrameManager.resizeFrames, 500);
        }
    },
    resizeFrames: function() {
        FrameManager.retrieveFrameIdAndHeight();
        if ((FrameManager.currentFrameId != FrameManager.lastFrameId) ||
(FrameManager.currentFrameHeight != FrameManager.lastFrameHeight)) {
            var iframe = document.getElementById(FrameManager.currentFrameId.toString());
            if (iframe == null) return;
            iframe.style.height = FrameManager.currentFrameHeight.toString() + "px";
            FrameManager.lastFrameId = FrameManager.currentFrameId;
            FrameManager.lastFrameHeight = FrameManager.currentFrameHeight;
            window.location.hash = '';
        }
    },
    retrieveFrameIdAndHeight: function() {
        if (window.location.hash.length == 0) return;
        var hashValue = window.location.hash.substring(1);
        if ((hashValue == null) || (hashValue.length == 0)) return;
        var pairs = hashValue.split('&');
        if ((pairs != null) && (pairs.length > 0)) {
            for(var i = 0; i < pairs.length; i++) {
                var pair = pairs[i].split('=');
                if ((pair != null) && (pair.length > 0)) {
                    if (pair[0] == 'frameId') {
                        if ((pair[1] != null) && (pair[1].length > 0)) {
                            FrameManager.currentFrameId = pair[1];
                        }
                    } else if (pair[0] == 'height') {
                        var height = parseInt(pair[1]);
                        if (!isNaN(height)) {
                            FrameManager.currentFrameHeight = height;
                            FrameManager.currentFrameHeight += 15;
                        }
                    }
                }
            }
        }
    },
    registerFrame: function(frame) {
        var currentLocation = location.href;
        var hashIndex = currentLocation.indexOf('#');
        if (hashIndex > -1) {
            currentLocation = currentLocation.substring(0, hashIndex);
        }
        frame.contentWindow.location = frame.src + '?frameId=' + frame.id + '#' + currentLocation;
    }
};
window.setTimeout(FrameManager.init, 300);
这个js里面会连续不断地执行resizeFrames这个函数，这个函数就是获得浏览器hash的值，
如果有值的话就调整iframe的高度

再来看看iframe里面的内容：
<script type="text/javascript" src="frame.js"></script>
<script type="text/javascript">
window.onload = function(event) {
   window.setInterval(publishHeight, 300);
}
</script>
需要引入一段js，然后每隔一定的时间调用一个publishHeight函数，这个js的内容如下：
function publishHeight() {
    if (window.location.hash.length == 0) return;
    var frameId = getFrameId();
    if (frameId == '') return;
    var actualHeight = getBodyHeight();
    var currentHeight = getViewPortHeight();
    if  (Math.abs(actualHeight - currentHeight) > 15) {
        var hostUrl = window.location.hash.substring(1);
        hostUrl += "#";
        hostUrl += 'frameId=' + frameId;
        hostUrl += '&';
        hostUrl += 'height=' + actualHeight.toString();
        window.top.location = hostUrl;
    }
}
function getFrameId() {
    var qs = parseQueryString(window.location.href);
    var frameId = qs["frameId"];
    var hashIndex = frameId.indexOf('#');
    if (hashIndex > -1) {
        frameId = frameId.substring(0, hashIndex);
    }
    return frameId;
}
function getBodyHeight() {
    var height,
        scrollHeight,
        offsetHeight;
    if (document.height) {
        height = document.height;
    } else if (document.body) {
        if (document.body.scrollHeight) {
            height = scrollHeight = document.body.scrollHeight;
        }
        if (document.body.offsetHeight) {
            height = offsetHeight = document.body.offsetHeight;
        }
        if (scrollHeight && offsetHeight) {
            height = Math.max(scrollHeight, offsetHeight);
        }
    }
    return height;
}
function getViewPortHeight() {
    var height = 0;
    if (window.innerHeight) {
        height = window.innerHeight - 18;
    } else if ((document.documentElement) && (document.documentElement.clientHeight)) {
        height = document.documentElement.clientHeight;
    } else if ((document.body) && (document.body.clientHeight)) {
        height = document.body.clientHeight;
    }
    return height;
}
function parseQueryString(url) {
    url = new String(url);
    var queryStringValues = new Object(),
        querystring = url.substring((url.indexOf('?') + 1), url.length),
        querystringSplit = querystring.split('&');
    for (i = 0; i < querystringSplit.length; i++) {
        var pair = querystringSplit[i].split('='),
            name = pair[0],
            value = pair[1];
        queryStringValues[name] = value;
    }
    return queryStringValues;
}
publishHeight这个函数会不断地将iframe的高度通过hash传给顶级窗口，看红色标示部分，
这样父窗口就可以获得hash的值，很关键。

了解更多请看：
http://css-tricks.com/cross-domain-iframe-resizing/
http://geekswithblogs.net/rashid/archive/2007/01/13/103518.aspx
http://adamfortuna.com/2009/09/30/resize-a-crossdomain-iframe/
http://blog.johnmckerrell.com/2006/10/22/resizing-iframes-across-domains/