H5横屏适配方案

横屏模式一般使用场景比较少，特殊情况除外，一般用于游戏、操作性比较大的网页会采用横屏

整体代码

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        #content {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
        }

        #myiframe{
            position: absolute;
            left: 0;
            top: 0;
            border: none;
            width: 100% !important;
            height: 100% !important;
            z-index: 1800;
        }
    </style>
</head>

<body>

    <div id="content">
        <iframe src="http://www.baidu.com" id="myiframe" scrolling="no" onload="changeFrameHeight()" frameborder="0"></iframe>
    </div>
    <script>
        function changeFrameHeight() {
            var ifm = document.getElementById("myiframe");
            ifm.height = document.documentElement.clientHeight;

        }

        window.onresize = function () {
            changeFrameHeight();

        }
        // 利用 CSS3 旋转 对根容器逆时针旋转 90 度
        var detectOrient = function () {
            var width = document.documentElement.clientWidth,
                height = document.documentElement.clientHeight,
                $wrapper = document.getElementById("content"),
                style = "";
            if (width >= height) { // 横屏
                style += "width:" + width + "px;";  // 注意旋转后的宽高切换
                style += "height:" + height + "px;";
                style += "-webkit-transform: rotate(0); transform: rotate(0);";
                style += "-webkit-transform-origin: 0 0;";
                style += "transform-origin: 0 0;";
                console.log(1)
            }
            else { // 竖屏
                style += "width:" + height + "px;";
                style += "height:" + width + "px;";
                style += "-webkit-transform: rotate(90deg); transform: rotate(90deg);";
                // 注意旋转中点的处理
                style += "-webkit-transform-origin: " + width / 2 + "px " + width / 2 + "px;";
                style += "transform-origin: " + width / 2 + "px " + width / 2 + "px;";
                console.log(2)
            }
            $wrapper.style.cssText = style;
        }
        window.onresize = detectOrient;
        detectOrient();
    </script>
</body>

</html>