flex属性详解

flex布局，父元素属性可参考：flex布局，本文主要介绍flex添加到子元素的属性。

  <div class="father">
    <div class="left"></div>
    <div class="middle"></div>
    <div class="middle"></div>
    <div class="middle"></div>
    <div class="right"></div>
  </div>

1、order

改变子元素的排列顺序，默认值为 0，可选参数：inherit | initial | unset ，可以为负值，数值越小排列越靠前。

.father{
  display: flex;
}
.left{
  order: 3;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: aquamarine;
}
.middle{
  order: -2;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: yellowgreen;
}
.right{
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: pink;
}

2、flex-grow

子元素弹性扩展的比例，可选参数：inherit | initial | unset ，也可以是数字，不能是负数，默认为 0。如果所有子元素的 flex-grow 的值都为数字的话，则会把父元素分为若干份，每个子元素根据 flex-grow 的值扩展。

.father{
  display: flex;
}
.left{
  flex-grow: 2;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: aquamarine;
}
.middle{
  flex-grow: 3;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: yellowgreen;
}
.right{
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: pink;
  flex-grow: 1;
}

.father{
  display: flex;
}
.left{
  flex-grow: 2;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: aquamarine;
}
.middle{
  flex-grow: 3;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: yellowgreen;
}
.middle-unset{
  flex-grow: unset;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: blueviolet;
}
.right{
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: pink;
  flex-grow: 1;
}

3、flex-shrink

控制子元素如何收缩，默认是 1，可选参数：inherit | initial | unset ，可以是 number ，不能为负数，一般写 flex-shrink:0，防止变廋。

.father{
  display: flex;
}
.left{
  flex-shrink: 1;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: aquamarine;
}
.middle{
  flex-shrink: 2;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: yellowgreen;
}
.middle-unset{
  flex-shrink: 3;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: blueviolet;
}
.right{
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: pink;
  flex-shrink: 0;
}

4、flex-basis

控制基准大小，默认是 auto，可选参数：inherit | initial | unset ，可以是 width 或 height，也可以是百分数，不能为负值，表示在不伸缩的情况下子容器的原始尺寸。横轴为主轴时，表宽度，主轴为纵向时代表高度。

.father{
  display: flex;
}
.left{
  flex-basis: 10%;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: aquamarine;
}
.middle{
  flex-basis: 100px;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: yellowgreen;
}
.middle-unset{
  flex-basis: 100px;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: blueviolet;
}
.right{
  flex-basis: 200px;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: pink;
}

5、align-self

单独定义子元素沿交叉轴排列的方式，可选参数：flex-start | center | flex-end | baseline | stretch，与align-items的使用方式基本相同。

.father{
  display: flex;
  height: 300px;
}
.left{
  align-self: center;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: aquamarine;
}
.middle{
  flex-basis: 100px;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: yellowgreen;
}
.middle-unset{
  flex-basis: 150px;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: blueviolet;
}
.right{
  align-self: flex-end;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: pink;
}