vue3 基于element-plus进行的一个可拖动改变导航与内容区域大小的简单方法

1、先上个截图：

说明：拖动上面的分隔栏就可以实现，改变左右区域的大小。

2、上面的例子来自官网的：

Container 布局容器 | Element Plus

3、拖动的效果来自：

https://juejin.cn/post/7029640316999172104#heading-1

4、我们将二个效果，进行了组合，代码：

<template>
  <el-container class="box" style="height: 100vh">
    <el-aside width="200px" class="left">
      <el-scrollbar>
        <el-menu :default-openeds="['1', '3']">
          <el-sub-menu index="1">
            <template #title>
              <el-icon><message /></el-icon>Navigator One
            </template>
            <el-menu-item-group>
              <template #title>Group 1</template>
              <el-menu-item index="1-1">Option 1</el-menu-item>
              <el-menu-item index="1-2">Option 2</el-menu-item>
            </el-menu-item-group>
            <el-menu-item-group title="Group 2">
              <el-menu-item index="1-3">Option 3</el-menu-item>
            </el-menu-item-group>
            <el-sub-menu index="1-4">
              <template #title>Option4</template>
              <el-menu-item index="1-4-1">Option 4-1</el-menu-item>
            </el-sub-menu>
          </el-sub-menu>
          <el-sub-menu index="2">
            <template #title>
              <el-icon><icon-menu /></el-icon>Navigator Two
            </template>
            <el-menu-item-group>
              <template #title>Group 1</template>
              <el-menu-item index="2-1">Option 1</el-menu-item>
              <el-menu-item index="2-2">Option 2</el-menu-item>
            </el-menu-item-group>
            <el-menu-item-group title="Group 2">
              <el-menu-item index="2-3">Option 3</el-menu-item>
            </el-menu-item-group>
            <el-sub-menu index="2-4">
              <template #title>Option 4</template>
              <el-menu-item index="2-4-1">Option 4-1</el-menu-item>
            </el-sub-menu>
          </el-sub-menu>
          <el-sub-menu index="3">
            <template #title>
              <el-icon><setting /></el-icon>Navigator Three
            </template>
            <el-menu-item-group>
              <template #title>Group 1</template>
              <el-menu-item index="3-1">Option 1</el-menu-item>
              <el-menu-item index="3-2">Option 2</el-menu-item>
            </el-menu-item-group>
            <el-menu-item-group title="Group 2">
              <el-menu-item index="3-3">Option 3</el-menu-item>
            </el-menu-item-group>
            <el-sub-menu index="3-4">
              <template #title>Option 4</template>
              <el-menu-item index="3-4-1">Option 4-1</el-menu-item>
            </el-sub-menu>
          </el-sub-menu>
        </el-menu>
      </el-scrollbar>
    </el-aside>
    <div class="resize"></div>
    <el-container class="mid">
      <el-header style="text-align: right; font-size: 12px">
        <div class="toolbar">
          <el-dropdown>
            <el-icon style="margin-right: 8px; margin-top: 1px">
              <setting />
            </el-icon>
            <template #dropdown>
              <el-dropdown-menu>
                <el-dropdown-item>View</el-dropdown-item>
                <el-dropdown-item>Add</el-dropdown-item>
                <el-dropdown-item>Delete</el-dropdown-item>
              </el-dropdown-menu>
            </template>
          </el-dropdown>
          <span>Tom</span>
        </div>
      </el-header>

      <el-main>
        <el-scrollbar>
          <el-table :data="tableData">
            <el-table-column prop="date" label="Date" width="140" />
            <el-table-column prop="name" label="Name" width="120" />
            <el-table-column prop="address" label="Address" />
          </el-table>
        </el-scrollbar>
      </el-main>
    </el-container>
  </el-container>
</template>

<script lang="ts" setup>
import { onMounted, onUnmounted, ref } from "vue";
import { Menu as IconMenu, Message, Setting } from "@element-plus/icons-vue";

const item = {
  date: "2016-05-02",
  name: "Tom",
  address: "No. 189, Grove St, Los Angeles",
};
const tableData = ref(Array.from({ length: 20 }).fill(item));

function dragControllerDiv() {
  var resize = document.getElementsByClassName("resize");
  var left = document.getElementsByClassName("left");
  var mid = document.getElementsByClassName("mid");
  var box = document.getElementsByClassName("box");
  for (let i = 0; i < resize.length; i++) {
    // 鼠标按下事件
    resize[i].onmousedown = function (e) {
      //颜色改变提醒
      resize[i].style.background = "#818181";
      var startX = e.clientX;
      resize[i].left = resize[i].offsetLeft;
      // 鼠标拖动事件
      document.onmousemove = function (e) {
        var endX = e.clientX;
        var moveLen = resize[i].left + (endX - startX); // （endx-startx）=移动的距离。resize[i].left+移动的距离=左边区域最后的宽度
        var maxT = box[i].clientWidth - resize[i].offsetWidth; // 容器宽度 - 左边区域的宽度 = 右边区域的宽度

        if (moveLen < 32) moveLen = 32; // 左边区域的最小宽度为32px
        if (moveLen > maxT - 150) moveLen = maxT - 150; //右边区域最小宽度为150px

        resize[i].style.left = moveLen; // 设置左侧区域的宽度

        for (let j = 0; j < left.length; j++) {
          left[j].style.width = moveLen + "px";
          mid[j].style.width = box[i].clientWidth - moveLen - 10 + "px";
        }
      };
      // 鼠标松开事件
      document.onmouseup = function (evt) {
        //颜色恢复
        resize[i].style.background = "#d6d6d6";
        document.onmousemove = null;
        document.onmouseup = null;
        resize[i].releaseCapture && resize[i].releaseCapture(); //当你不在需要继续获得鼠标消息就要应该调用ReleaseCapture()释放掉
      };
      resize[i].setCapture && resize[i].setCapture(); //该函数在属于当前线程的指定窗口里设置鼠标捕获
      return false;
    };
  }
}

onMounted(() => {
  dragControllerDiv();
});
</script>

<style scoped>
.layout-container-demo .el-header {
  position: relative;
  background-color: var(--el-color-primary-light-7);
  color: var(--el-text-color-primary);
}
.layout-container-demo .el-aside {
  color: var(--el-text-color-primary);
  background: var(--el-color-primary-light-8);
}
.layout-container-demo .el-menu {
  border-right: none;
}
.layout-container-demo .el-main {
  padding: 0;
}
.layout-container-demo .toolbar {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  right: 20px;
}

/* 拖拽相关样式 */
/*包围div样式*/
.box {
  width: 100%;
  height: 100%;
  margin: 1% 0px;
  overflow: hidden;
  box-shadow: -1px 9px 10px 3px rgba(0, 0, 0, 0.11);
}
/*左侧div样式*/
.left {
  width: calc(32% - 10px); /*左侧初始化宽度*/
  height: 100%;
  background: #ffffff;
  float: left;
}
/*拖拽区div样式*/
.resize {
  cursor: col-resize;
  float: left;
  position: relative;
  top: 45%;
  background-color: #d6d6d6;
  border-radius: 5px;
  margin-top: -10px;
  width: 10px;
  height: 50px;
  background-size: cover;
  background-position: center;
  /*z-index: 99999;*/
  font-size: 32px;
  color: white;
}
/*拖拽区鼠标悬停样式*/
.resize:hover {
  color: #444444;
}
/*右侧div'样式*/
.mid {
  float: left;
  width: 68%; /*右侧初始化宽度*/
  height: 100%;
  background: #fff;
  box-shadow: -1px 4px 5px 3px rgba(0, 0, 0, 0.11);
}
</style>

5、通过上面的代码，我们可以很轻松的实现拖动改变左右二侧区域的大小，说明：

document.getElementsByClassName：返回一个类似数组的对象,包含了所有指定 class 名称的子元素。比如document.getElementsByClassName("left"); 是查找class="left"的所有的elements。

document.onmousemove = function (e) {
        var endX = e.clientX;
        var moveLen = resize[i].left + (endX - startX); // （endx-startx）=移动的距离。resize[i].left+移动的距离=左边区域最后的宽度
        var maxT = box[i].clientWidth - resize[i].offsetWidth; // 容器宽度 - 左边区域的宽度 = 右边区域的宽度

        if (moveLen < 32) moveLen = 32; // 左边区域的最小宽度为32px
        if (moveLen > maxT - 150) moveLen = maxT - 150; //右边区域最小宽度为150px

        resize[i].style.left = moveLen; // 设置左侧区域的宽度

        for (let j = 0; j < left.length; j++) {
          left[j].style.width = moveLen + "px";
          mid[j].style.width = box[i].clientWidth - moveLen - 10 + "px";
        }
      };

这里的left[j],mid[j], length=1的时候，就是第一个元素，也就是我们左侧导航与右侧数据。

容器宽度 = 左边区域的宽度 + resize的宽度 + 右边区域的宽度

resize[0]的left就是左侧的宽度。