彻底分清clientHeight，scrollHeight，offsetHeight，clientTop，scrollTop，offsetTop的区别

clientHeight，scrollHeight，offsetHeight

clientHeight: 可理解为内部可视区高度，样式的height+上下padding
scrollHeight: 内容的实际高度+上下padding（如果没有限制div的height，即height是自适应的，一般是scrollHeight==clientHeight）
offsetHeight:可理解为div的可视高度，样式的height+上下padding+上下border-width。

clientTop，scrollTop，offsetTop

clientTop: 容器内部相对于容器本身的top偏移，实际就是上border-width （div1是10px，div2是20px）

scrollTop: Y轴的滚动条没有，或滚到最上时，是0；y轴的滚动条滚到最下时是 scrollHeight-clientHeight（很好理解）

offsetTop: 容器到其包含块顶部的距离，粗略的说法可以理解为其父元素。 offsetTop = top + margin-top + border-top

滚动时通常我们只能scrollTop，当scrollTop为 0 到 scrollHeight-clientHeight 是正常的滚动距离，否则就是滚动过头了（手机上的上下拉取）！

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>
        * {
            margin: 0;
            padding: 0;
        }

        div {
            margin: 20px;
            border: 10px solid gray;
            padding: 10px;
        }

        #wrapper {
            position: relative;
        }

        #div1,
        #div2 {
            height: 200px;
            width: 200px;
        }

        #tip1,
        #tip2 {
            position: absolute;
            margin: 0;
            right: 100px;
            height: 150px;
        }

        #tip1 {
            top: 50px;
        }

        #tip2 {
            top: 300px;
        }

        #div1 {
            overflow: scroll;
        }
    </style>
</head>

<body>
    <div id="wrapper">
        <div id="div1">
            <p style="height:300px;border: 2px solid red"></p>
            <div id="tip1">
                <p>div1</p>
                <p>clientHeight：<span id="clientHeight1"></span></p>
                <p>scrollHeight：<span id="scrollHeight1"></span></p>
                <p>offsetHeight：<span id="offsetHeight1"></span></p>
                <p>clientTop：<span id="clientTop1"></span></p>
                <p>scrollTop：<span id="scrollTop1"></span></p>
                <p>offsetTop：<span id="offsetTop1"></span></p>
            </div>
        </div>
        <div id="div2" style="border:20px solid">
            <div id="tip2">
                <p>div2</p>
                <p>clientHeight：<span id="clientHeight2"></span></p>
                <p>scrollHeight：<span id="scrollHeight2"></span></p>
                <p>offsetHeight：<span id="offsetHeight2"></span></p>
                <p>clientTop：<span id="clientTop2"></span></p>
                <p>scrollTop：<span id="scrollTop2"></span></p>
                <p>offsetTop：<span id="offsetTop2"></span></p>
            </div>
        </div>
    </div>

</body>
<script>
    clientHeight1.innerHTML = div1.clientHeight
    scrollHeight1.innerHTML = div1.scrollHeight
    offsetHeight1.innerHTML = div1.offsetHeight
    clientTop1.innerHTML = div1.clientTop
    scrollTop1.innerHTML = div1.scrollTop
    offsetTop1.innerHTML = div1.offsetTop
    clientHeight2.innerHTML = div2.clientHeight
    scrollHeight2.innerHTML = div2.scrollHeight
    offsetHeight2.innerHTML = div2.offsetHeight
    clientTop2.innerHTML = div2.clientTop
    scrollTop2.innerHTML = div2.scrollTop
    offsetTop2.innerHTML = div2.offsetTop


</script>

</html>

彻底分清clientHeight，scrollHeight，offsetHeight，clientTop，scrollTop，offsetTop的区别

clientHeight，scrollHeight，offsetHeight

clientTop，scrollTop，offsetTop

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