前端vue左侧树的一整套功能实现（一）：vue2+vite封装v-resize指令，实现左侧树拖拽宽度和折叠展开
实现v-resize指令，具体以下功能：
- 指令接收宽度最大最小值，接收一个id用于localStorage存储拖拽宽度，接收padding
- 拖拽时产生虚线拖拽，松开鼠标再进行元素宽度调整
- 折叠展开图标使用本地图片
封装一个vite下使用本地图片的函数方法
用于拖拽指令中设置折叠展开图标
/** vite使用动态图片的方式 */
export function requireImg(name) {return new URL(`/src/assets/imgs/${name}`, import.meta.url).href
}
v-resize指令具体代码
// 注意，需要去除绑定元素的overflow:auto，指令会添加一个具有overflow:auto的元素
let resize;
let stopResize;
const vResize = {bind(el, binding) {// 从绑定值中获取最小宽度和最大宽度const {minWidth = 150,maxWidth = 400,id = '',padding = 10,} = binding.value || {};// 拖拽元素内部插入一个包裹元素，方便控制所有子元素隐藏显示const wrapper = document.createElement('div');wrapper.style.cssText = `width: 100%; height: 100%; overflow: auto; padding:${padding}px`;while (el.firstChild) {// appendChild 方法用于将一个节点添加到另一个节点的子节点列表的末尾。// 如果要添加的节点已经存在于文档树中，appendChild 方法会将该节点从其当前位置移动到新的位置，而不是复制该节点。// 这样就可以将 el 的所有子元素通过循环全部插入至 wrapper 中wrapper.appendChild(el.firstChild);}el.appendChild(wrapper);// 创建拖拽元素const resizer = document.createElement('div');resizer.style.cssText ='width: 10px; height: 100%; position: absolute; right: -10px; top: 0px; cursor: ew-resize; user-select: none; display: flex; justify-content: center; align-items: center; z-index: 999;';el.style.position = 'relative';el.style.padding = '0px';el.appendChild(resizer);el.style.transition = 'width 0.3s ease';// 缓存宽度const savedWidth = localStorage.getItem('WIDTH' + id);if (savedWidth) {el.style.width = savedWidth;if (el.style.width === '0px') {wrapper.style.display = 'none';}}// 创建切换按钮const img = document.createElement('img');img.src =el.style.width === '0px'? requireImg('tree/7.png'): requireImg('tree/6.png');img.style.cssText = 'cursor:pointer;height:40px;';resizer.appendChild(img);// 切换显示/隐藏逻辑img.addEventListener('mousedown', (e) => {e.stopPropagation();toggleContainer(el, wrapper, img);});// 拖拽虚线const line = document.createElement('div');line.style.cssText ='position: absolute; height: 100%; width: 2px; right: 0; top: 0; z-index: 9999; border-right: 0px dashed #409EFF; pointer-events: none;';el.appendChild(line);// 拖拽事件resizer.addEventListener('mousedown', () => {document.addEventListener('mousemove', resize);document.addEventListener('mouseup', stopResize);});let newWidth;resize = function (e) {line.style.borderRight = '2px dashed #409EFF';// 使用传入的最小宽度和最大宽度const width = e.pageX - el.getBoundingClientRect().left;if (width <= 0) {newWidth = 0;} else {newWidth = Math.max(minWidth, Math.min(maxWidth, width));}line.style.right = `${el.getBoundingClientRect().right - e.pageX}px`;};stopResize = function () {line.style.borderRight = '0px dashed #409EFF';document.removeEventListener('mousemove', resize);document.removeEventListener('mouseup', stopResize);if (newWidth) {el.style.width = `${newWidth}px`;setTimeout(() => {wrapper.style.display = 'block';}, 200);} else {el.style.width = `0px`;wrapper.style.display = 'none';}img.src =newWidth === 0 ? requireImg('tree/7.png') : requireImg('tree/6.png');localStorage.setItem('WIDTH' + id, el.style.width);};function toggleContainer(el, wrapper, img) {if (el.style.width === '0px') {el.style.width = `${minWidth}px`;img.src = requireImg('tree/6.png');setTimeout(() => {wrapper.style.display = 'block';}, 200);} else {wrapper.style.display = 'none';el.style.width = '0px';img.src = requireImg('tree/7.png');}localStorage.setItem('WIDTH' + id, el.style.width);}},unbind() {// 清除所有事件监听器，防止内存泄漏document.removeEventListener('mousemove', resize);document.removeEventListener('mouseup', stopResize);},
};Vue.directive('resize', vResize);
使用指令
<div class="page"><divclass="left"v-resize="{id: 'left_tree',minWidth: '473',maxWidth: '773',}"v-loading="treeloading">...</div><div class="right">...</div></div>
.page{display:flex;.left_tree{width:550px;}.right{flex:1;}
}