盒模型常用元素属性之大小、位置

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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>盒模型常用元素属性之大小、位置</title>
    <style>
        .box{
            width: 300px;
            height: 300px;
            background: #7FFFD4;
            position: relative;
            border: 2px solid #000;
            padding: 10px;
            box-sizing: border-box;
            /*
            box-sizing:border-box    boxWidth=content+padding+border
            box-sizing:content-box   boxWidth=content
            */
        }
        .box1{
            width: 100px;
            height: 100px;
            background: #7f7f7f;
            /*垂直水平居中*/
            position: absolute;
            margin: auto;
            top: 0;
            bottom: 0;
            left: 0;
            right: 0;
        }
    </style>
</head>
<body>
<div class="box">
    <div class="box1"></div>
</div>
<script>
    const html = document.documentElement;//返回文档的根节点html
    console.log(html.clientWidth);//clientWidth = contentWidth + 左右padding
    console.log(html.clientHeight);//clientHeight = contentHeight + 上下padding
    /*
     *下面两个一般不用
     * clientTop = borderTop 上边框宽度
     * clientLeft = borderLeft 左边框宽度
     */
    const box = document.querySelector(".box");
    console.log("box.clientWidth:" + box.clientWidth);
    console.log("box.offsetWidth:" + box.offsetWidth);
    /*
     * offsetWidth = contentWidth + 左右padding + 左右border
     * offsetHeight = contentHeight + 上下padding + 上下border
     * offsetTop: 当前元素上边框（外边缘）到定位父级（没有定位父级就是body）上边框（内边缘）的距离
     * offsetLeft:当前元素左边框（外边缘）到定位父级（没有定位父级就是body）左边框（内边缘）的距离
     */
    html.style.height = 2000 + "px";
    console.log(html.scrollHeight);//当前文档的实际高度  同理scrollWidth
    console.log(html.clientHeight);//当前文档可视区高度
    console.log(html.scrollTop);//当前文档可视区顶部到文档顶部的距离 同理scrollLeft
</script>
</body>
</html>
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