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2、overflow:hidden清楚浮动的原理 #2

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shengq666 opened this issue Jun 23, 2020 · 1 comment

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shengq666 commented Jun 23, 2020

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shengq666 commented Jun 23, 2020

今天突然想到BFC，就想到了 overflow:hidden 可以触发BFC。就有点疑惑为啥该操作可以清楚浮动，它的本意不是用来超出隐藏的吗？

网上搜了一番在知乎上看到 貘吃馍香 的回答，颇获收益，答案如下：

overflow:hidden 的意思是超出的部分要裁切隐藏掉
那么如果 float 的元素不占普通流位置
普通流的包含块要根据内容高度裁切隐藏
如果高度是默认值auto
那么不计算其内浮动元素高度就裁切，就有可能会裁掉float
这是反布局常识的

所以如果没有明确设定容器高情况下
它要计算内容全部高度才能确定在什么位置hidden
浮动的高度就要被计算进去
顺带达成了清理浮动的目标
同理
overflow 非默认值
position 非默认值
float 非默认值等都是遵循这个布局计算思路

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