问题描述
在开发中遇到一个需求，即实现table列的拖拽，但是调研发现，大部分是基于sorttable.js这个包实现的，但是通过实际应用，发现sorttable.js用在操作element table 组件中并不是很舒服，总会莫名其妙的冒出一些异常bug，于是自行封装一个table 列拖拽组件。
难点概括
①element table header插槽应用
②drag知识点应用
③splice()方法理解
演示代码
<template><div><h1>基于element-ui table列拖拽实现</h1><drag-head :head-columns="tableHead" :data="tableData"></drag-head></div>
</template>
<script>
import DragHead from "./dragHead.vue";export default {name: "DragHeadCase",components: { DragHead },data() {return {tableHead: [{label: "零零",prop: "v0",width: 150,},{label: "一一",prop: "v1",width: 150,},{label: "二二",prop: "v2",width: 150,},{label: "三三",prop: "v3",width: 150,},{label: "四四",prop: "v4",width: 300,},{label: "五五",prop: "v5",},{label: "六六",prop: "v6",},{label: "七七",prop: "v7",},{label: "八八",prop: "v8",},{label: "九九",prop: "v9",},],tableData: [{v0: "2016-05-02",v1: "王小虎",v2: "上海",v3: "普陀区",v4: "上海市普陀区金沙江路 1518 弄",v5: 200333,v6: "2016-05-02",v7: "王小虎",v8: "上海",v9: "普陀区",},{v0: "2016-05-02",v1: "王小虎",v2: "上海",v3: "普陀区",v4: "上海市普陀区金沙江路 1518 弄",v5: 200333,v6: "2016-05-02",v7: "王小虎",v8: "上海",v9: "普陀区",},{v0: "2016-05-02",v1: "王小虎",v2: "上海",v3: "普陀区",v4: "上海市普陀区金沙江路 1518 弄",v5: 200333,v6: "2016-05-02",v7: "王小虎",v8: "上海",v9: "普陀区",},{v0: "2016-05-02",v1: "王小虎",v2: "上海",v3: "普陀区",v4: "上海市普陀区金沙江路 1518 弄",v5: 200333,v6: "2016-05-02",v7: "王小虎",v8: "上海",v9: "普陀区",},{v0: "2016-05-02",v1: "王小虎",v2: "上海",v3: "普陀区",v4: "上海市普陀区金沙江路 1518 弄",v5: 200333,v6: "2016-05-02",v7: "王小虎",v8: "上海",v9: "普陀区",},],};},
};
</script>
table 列 拖拽组件实现代码
<template><div style="width: 1000px"><el-tableref="elTable"borderstyle="width: 100%"v-bind="$attrs"v-on="$listeners":key="headKey":cell-class-name="cellClassName":header-cell-class-name="cellClassName"><!-- 循环表头 --><template v-for="(col, index) in tableHead"><el-table-column:key="index":prop="col.prop":align="col.align || 'center'":width="col.width || 100"><!-- 通过插槽为表头绑定mousedown和dragover方法 --><template slot="header" slot-scope="{ column, $index }"><span@mousedown="handleMounseDown($event, column, $index)"@dragover="handleDragover($event, column, $index)">{{ col.label }}</span></template></el-table-column></template></el-table></div>
</template><script>
export default {props: {headColumns: Array,},mounted() {/** 备用操作（如果需要对headColumns数组操作） */this.tableHead = this.headColumns;},data() {return {tableHead: [],// 拖拽状态dragState: {start: -3, // 起始元素的 index 防止初始化cellStyle时序号、展开等默认样式改变，最好小于-3end: -3, // 移动鼠标时所覆盖的元素 indexdragging: false, // 是否正在拖动direction: undefined, // 拖动方向},headKey: "dragHead", // 表头数组变换位置时，重绘table（不更新该值，表头数组变化时，页面不会改变）scrollX: 0, // 初始x轴scroll位置（用于定位X轴滚动条）};},methods: {/** 鼠标摁下触发 */handleMounseDown(e, column, $index) {this.dragState.dragging = true;this.dragState.start = parseInt($index - 0);// 添加鼠标抬起事件 消除鼠标摁下立刻松开问题document.addEventListener("mouseup", this.handleMouseUp);// 添加拖拽结束事件document.addEventListener("dragend", this.handleMouseUp);// 对选中的表头允许其拖拽const dragclass = ".el-table__header-wrapper ." + column.id;const dragDom = document.querySelectorAll(dragclass);dragDom.forEach((dom) => {// 允许表头块可以被拖拽 draggable 属性 不允许拖拽dragover等相关拖拽事件无法触发dom.setAttribute("draggable", true);});},/** 鼠标在拖拽移动时触发 */handleDragover(e, column, $index) {if (this.dragState.dragging) {// 获取当前滚动条的位置const scrollDom = this.$refs.elTable.bodyWrapper;this.scrollX = scrollDom.scrollLeft;const index = parseInt($index - 0); // 记录起始列/** 实时更改鼠标处于表头的位置 */if (index - this.dragState.start !== 0) {this.dragState.direction =index - this.dragState.start < 0 ? "left" : "right"; // 判断拖动方向this.dragState.end = parseInt($index - 0);} else {this.dragState.end = this.dragState.start;this.dragState.direction = null;}}},/** 鼠标抬起或拖拽结束触发 */handleMouseUp() {// 更新拖拽后的表头this.headDraged(this.dragState);const { end } = this.dragState;// 初始化拖动状态this.dragState = {start: end, //记录最后拖动的位置end: -9,dragging: false,direction: undefined,};document.removeEventListener("mouseup", this.handleMouseUp);document.removeEventListener("dragend", this.handleMouseUp);setTimeout(() => {// 重置拖拽状态this.dragState.start = -9;}, 500);},// 更新拖拽后的表头headDraged({ start, end, direction }) {if (direction) {const originColumn = this.tableHead[start];// 有位置交换时，原先位置的元素删除，再在目标处插入this.tableHead.splice(start, 1);this.tableHead.splice(end, 0, originColumn);this.headKey = new Date().getTime() + ""; // 更新table key值this.$nextTick(() => {// 因为表头重绘后滚动条会移到最左端初始位置，因此如果是在中间部分拖拽，还需要把滚动条在定位到该位置this.$refs.elTable.bodyWrapper.scrollLeft = this.scrollX;});}},// 拖动虚线样式设置cellClassName({ columnIndex }) {const { start, end, direction } = this.dragState;const target = columnIndex - 0;if (target === start) {// 被移动的元素return "drag_start";} else if (target === end) {// 要移动的位置return `drag_end_${direction}`;}return "";},},
};
</script><style lang="scss" scoped>
::v-deep .el-table {.drag_start {opacity: 0.8;background-color: rgba(0, 0, 0, 0.938);color: #f3e8e8fd;transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);}.drag_end_left {border-left: 2px dotted rgba(0, 0, 0, 0.938);}.drag_end_right {border-right: 2px dotted rgba(0, 0, 0, 0.938);}
}
</style>
然后我在操作的时候碰到一个报错
[Violation ] Added non-passive event listener to ascroll- blocking 'mousewheel’event Consider marking event handler as ’ passive’to make the page more responsive. See https: com/feature/574554 3795965952
翻译：
[冲突]在ascroll中添加了非被动事件侦听器-阻塞“mousewheel”事件考虑将事件处理程序标记为“passive”，以使页面更具响应性。参见https:com/feature/574554 3795965952
解决办法：
npm i default-passive-events -S main.js import 'default-passive-events'
最后
该组件目前仅支持最简单的拖拽效果，后续开发出兼容fixed、checkbox、expand 以及操作列的组件会及时更新文章，有兴趣的朋友可以点赞收藏。
参考文献
基于element UI 实现 table 列 拖拽_element table列拖拽_淡然自若_blog的博客-CSDN博客
Added non-passive event listener to ascroll- blocking ‘mousewheel‘event Consider marking event handl_绅士的可怖的博客-CSDN博客
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