前端导出Excel，让后端刮目相看（前端导出Excel的方法)
前言
今天再开发中遇到一件事情，就是怎样用查询到的表格导出excel文件？网上有许多方法，最多的就是用数据流的方式。后端给出的方案也是提供一个借口，访问后的到一个文件，然后前端建立虚拟dom进行下载。 我看到网上有说这一块工作也可以前端去实现便使我灵光一闪。
导入依赖
// npm npm install -S file-saver xlsx npm install -D script-loader 复制代码
导入Bolb.js与Export2Excel.js
首先拷贝以下两个文件代码： Export2Excel.js
/* eslint-disable */ require('script-loader!file-saver'); require('script-loader!vendor/Blob'); require('script-loader!xlsx/dist/xlsx.core.min'); function generateArray(table) { var out = []; var rows = table.querySelectorAll('tr'); var ranges = []; for (var R = 0; R < rows.length; ++R) { var outRow = []; var row = rows[R]; var columns = row.querySelectorAll('td'); for (var C = 0; C < columns.length; ++C) { var cell = columns[C]; var colspan = cell.getAttribute('colspan'); var rowspan = cell.getAttribute('rowspan'); var cellValue = cell.innerText; if (cellValue !== "" && cellValue == +cellValue) cellValue = +cellValue; //Skip ranges ranges.forEach(function (range) { if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) { for (var i = 0; i <= range.e.c - range.s.c; ++i) outRow.push(null); } }); //Handle Row Span if (rowspan || colspan) { rowspan = rowspan || 1; colspan = colspan || 1; ranges.push({s: {r: R, c: outRow.length}, e: {r: R + rowspan - 1, c: outRow.length + colspan - 1}}); } ; //Handle Value outRow.push(cellValue !== "" ? cellValue : null); //Handle Colspan if (colspan) for (var k = 0; k < colspan - 1; ++k) outRow.push(null); } out.push(outRow); } return [out, ranges]; }; function datenum(v, date1904) { if (date1904) v += 1462; var epoch = Date.parse(v); return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000); } function sheet_from_array_of_arrays(data, opts) { var ws = {}; var range = {s: {c: 10000000, r: 10000000}, e: {c: 0, r: 0}}; for (var R = 0; R != data.length; ++R) { for (var C = 0; C != data[R].length; ++C) { if (range.s.r > R) range.s.r = R; if (range.s.c > C) range.s.c = C; if (range.e.r < R) range.e.r = R; if (range.e.c < C) range.e.c = C; var cell = {v: data[R][C]}; if (cell.v == null) continue; var cell_ref = XLSX.utils.encode_cell({c: C, r: R}); if (typeof cell.v === 'number') cell.t = 'n'; else if (typeof cell.v === 'boolean') cell.t = 'b'; else if (cell.v instanceof Date) { cell.t = 'n'; cell.z = XLSX.SSF._table[14]; cell.v = datenum(cell.v); } else cell.t = 's'; ws[cell_ref] = cell; } } if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range); return ws; } function Workbook() { if (!(this instanceof Workbook)) return new Workbook(); this.SheetNames = []; this.Sheets = {}; } function s2ab(s) { var buf = new ArrayBuffer(s.length); var view = new Uint8Array(buf); for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF; return buf; } export function export_table_to_excel(id) { var theTable = document.getElementById(id); console.log('a') var oo = generateArray(theTable); var ranges = oo[1]; /* original data */ var data = oo[0]; var ws_name = "SheetJS"; console.log(data); var wb = new Workbook(), ws = sheet_from_array_of_arrays(data); /* add ranges to worksheet */ // ws['!cols'] = ['apple', 'banan']; ws['!merges'] = ranges; /* add worksheet to workbook */ wb.SheetNames.push(ws_name); wb.Sheets[ws_name] = ws; var wbout = XLSX.write(wb, {bookType: 'xlsx', bookSST: false, type: 'binary'}); saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}), "test.xlsx") } function formatJson(jsonData) { console.log(jsonData) } export function export_json_to_excel(th, jsonData, defaultTitle) { /* original data */ var data = jsonData; data.unshift(th); var ws_name = "SheetJS"; var wb = new Workbook(), ws = sheet_from_array_of_arrays(data); /* add worksheet to workbook */ wb.SheetNames.push(ws_name); wb.Sheets[ws_name] = ws; var wbout = XLSX.write(wb, {bookType: 'xlsx', bookSST: false, type: 'binary'}); var title = defaultTitle || '列表' saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}), title + ".xlsx") } 复制代码Blob.js
(function (view) { "use strict"; view.URL = view.URL || view.webkitURL; if (view.Blob && view.URL) { try { new Blob; return; } catch (e) {} } // Internally we use a BlobBuilder implementation to base Blob off of // in order to support older browsers that only have BlobBuilder var BlobBuilder = view.BlobBuilder || view.WebKitBlobBuilder || view.MozBlobBuilder || (function(view) { var get_class = function(object) { return Object.prototype.toString.call(object).match(/^\[object\s(.*)\]$/)[1]; } , FakeBlobBuilder = function BlobBuilder() { this.data = []; } , FakeBlob = function Blob(data, type, encoding) { this.data = data; this.size = data.length; this.type = type; this.encoding = encoding; } , FBB_proto = FakeBlobBuilder.prototype , FB_proto = FakeBlob.prototype , FileReaderSync = view.FileReaderSync , FileException = function(type) { this.code = this[this.name = type]; } , file_ex_codes = ( "NOT_FOUND_ERR SECURITY_ERR ABORT_ERR NOT_READABLE_ERR ENCODING_ERR " + "NO_MODIFICATION_ALLOWED_ERR INVALID_STATE_ERR SYNTAX_ERR" ).split(" ") , file_ex_code = file_ex_codes.length , real_URL = view.URL || view.webkitURL || view , real_create_object_URL = real_URL.createObjectURL , real_revoke_object_URL = real_URL.revokeObjectURL , URL = real_URL , btoa = view.btoa , atob = view.atob , ArrayBuffer = view.ArrayBuffer , Uint8Array = view.Uint8Array ; FakeBlob.fake = FB_proto.fake = true; while (file_ex_code--) { FileException.prototype[file_ex_codes[file_ex_code]] = file_ex_code + 1; } if (!real_URL.createObjectURL) { URL = view.URL = {}; } URL.createObjectURL = function(blob) { var type = blob.type , data_URI_header ; if (type === null) { type = "application/octet-stream"; } if (blob instanceof FakeBlob) { data_URI_header = "data:" + type; if (blob.encoding === "base64") { return data_URI_header + ";base64," + blob.data; } else if (blob.encoding === "URI") { return data_URI_header + "," + decodeURIComponent(blob.data); } if (btoa) { return data_URI_header + ";base64," + btoa(blob.data); } else { return data_URI_header + "," + encodeURIComponent(blob.data); } } else if (real_create_object_URL) { return real_create_object_URL.call(real_URL, blob); } }; URL.revokeObjectURL = function(object_URL) { if (object_URL.substring(0, 5) !== "data:" && real_revoke_object_URL) { real_revoke_object_URL.call(real_URL, object_URL); } }; FBB_proto.append = function(data/*, endings*/) { var bb = this.data; // decode data to a binary string if (Uint8Array && (data instanceof ArrayBuffer || data instanceof Uint8Array)) { var str = "" , buf = new Uint8Array(data) , i = 0 , buf_len = buf.length ; for (; i < buf_len; i++) { str += String.fromCharCode(buf[i]); } bb.push(str); } else if (get_class(data) === "Blob" || get_class(data) === "File") { if (FileReaderSync) { var fr = new FileReaderSync; bb.push(fr.readAsBinaryString(data)); } else { // async FileReader won't work as BlobBuilder is sync throw new FileException("NOT_READABLE_ERR"); } } else if (data instanceof FakeBlob) { if (data.encoding === "base64" && atob) { bb.push(atob(data.data)); } else if (data.encoding === "URI") { bb.push(decodeURIComponent(data.data)); } else if (data.encoding === "raw") { bb.push(data.data); } } else { if (typeof data !== "string") { data += ""; // convert unsupported types to strings } // decode UTF-16 to binary string bb.push(unescape(encodeURIComponent(data))); } }; FBB_proto.getBlob = function(type) { if (!arguments.length) { type = null; } return new FakeBlob(this.data.join(""), type, "raw"); }; FBB_proto.toString = function() { return "[object BlobBuilder]"; }; FB_proto.slice = function(start, end, type) { var args = arguments.length; if (args < 3) { type = null; } return new FakeBlob( this.data.slice(start, args > 1 ? end : this.data.length) , type , this.encoding ); }; FB_proto.toString = function() { return "[object Blob]"; }; FB_proto.close = function() { this.size = this.data.length = 0; }; return FakeBlobBuilder; }(view)); view.Blob = function Blob(blobParts, options) { var type = options ? (options.type || "") : ""; var builder = new BlobBuilder(); if (blobParts) { for (var i = 0, len = blobParts.length; i < len; i++) { builder.append(blobParts[i]); } } return builder.getBlob(type); }; }(typeof self !== "undefined" && self || typeof window !== "undefined" && window || this.content || this)); 复制代码因为我们在Export2Excel.js中设置的Blob路径为vendor，所以我们要在src下建立相关文件夹并放入这两个js。
设置导出表格数据
假设我们需要导出一个这样的表格
数据
// data dataList: [ { name: "张明", loginTime: 16, id: 1, department: "生产部", sex: "男" }, { name: "小金", loginTime: 11, id: 2, department: "生产部", sex: "女" }, { name: "小凌", loginTime: 21, id: 3, department: "生产部", sex: "男" }, { name: "盖伦", loginTime: 5, id: 4, department: "测试部", sex: "男" } ] 复制代码html
<table border> <tr> <th>ID</th> <th>名称</th> <th>登陆次数</th> <th>部门</th> </tr> <tr v-for="item in dataList" :key="item.id"> <td>{{ item.id }}</td> <td>{{ item.name }}</td> <td>{{ item.loginTime }}</td> <td>{{ item.department }}</td> </tr> </table> <button @click="exportExcel">导出信息</button> 复制代码methods
// 导出excel exportExcel() { // 引入文件 const { export_json_to_excel } = require("vendor/Export2Excel.js"); // 表头 const tHeader = ["ID", "名称", "登陆次数", "部门"]; // table表格中对应的属性名 const filterVal = ["id", "name", "loginTime", "department"]; // 表格绑定数据转json const data = this.formatJson(filterVal, this.dataList); export_json_to_excel( tHeader, data, "部门登陆信息" + new Date().toLocaleDateString() ); // 对应下载文件的名字 }, // 导出列表格式化数据的方法 formatJson(filterVal, jsonData) { return jsonData.map(v => filterVal.map(j => v[j])); } 复制代码展示效果
到此，前端导出功能实现。这种方式的优势在于:1.不用请求后端获取文件。2.所见即所得，前端可有灵活地把控输出的数据，不用因为导出的数据有差错而拉着后端一起联调。
多sheet导出
我们可能有时候会遇到对Excel多sheet的操作，比如部门的多季度绩效分多sheet导出。
我们需要在Export2Excel.js中添加一个方法:
/** * 多sheet导出 * @param {Array} th 表头 * @param {Array} jsonDatas 数据集 * @param {String} defaultTitle 导出的excel名称 * @param {Array} sheetNames sheet名称集 */ export function export_season_to_excel(th, jsonDatas, defaultTitle, sheetNames) { var wb = new Workbook() jsonDatas.forEach((item, index) => { var data = item; data.unshift(th); var ws_name = sheetNames[index]; var ws = sheet_from_array_of_arrays(data); /* add worksheet to workbook */ wb.SheetNames.push(ws_name); wb.Sheets[ws_name] = ws; }) var wbout = XLSX.write(wb, { bookType: 'xlsx', bookSST: false, type: 'binary' }); var title = defaultTitle || '列表' saveAs(new Blob([s2ab(wbout)], { type: "application/octet-stream" }), title + ".xlsx") } 复制代码页面中的data内容：
// data 季度绩效数据 seasonDatas: [ [ { name: "张明", score: 72 }, { name: "小金", score: 21 }, { name: "小凌", score: 16 }, { name: "盖伦", score: 84 } ], [ { name: "张明", score: 32 }, { name: "小金", score: 54 }, { name: "小凌", score: 45 }, { name: "盖伦", score: 26 } ], [ { name: "张明", score: 67 }, { name: "小金", score: 87 }, { name: "小凌", score: 45 }, { name: "盖伦", score: 78 } ], [ { name: "张明", score: 54 }, { name: "小金", score: 34 }, { name: "小凌", score: 26 }, { name: "盖伦", score: 34 } ] ] 复制代码html
<div class="season"> <template v-for="(item, index) in seasonDatas"> <div :key="index"> {{ `第${index + 1}季度绩效` }} <table border> <tr> <th>名称</th> <th>绩效分</th> </tr> <tr v-for="(scoreItem, scoreindex) in item" :key="scoreindex"> <td>{{ scoreItem.name }}</td> <td>{{ scoreItem.score }}</td> </tr> </table> </div> </template> </div> <button @click="exportSeason">导出绩效信息</button> 复制代码执行方法
// methods 导出绩效信息excel exportSeason() { // 引入文件 const { export_season_to_excel } = require("vendor/Export2Excel.js"); // 表头 const tHeader = ["名称", "绩效分"]; // table表格中对应的属性名 const filterVal = ["name", "score"]; let datas = []; let sheets = []; this.seasonDatas.forEach((item, index) => { // 表格绑定数据转json datas.push(this.formatJson(filterVal, item)); sheets.push(`第${index + 1}季度绩效`); }); export_season_to_excel( tHeader, datas, "部门季度绩效" + new Date().toLocaleDateString(), sheets ); // 对应下载文件的名字 }, 复制代码展示效果：
至此，多Sheet导出我们也完成了。
作者：有趣的老凌
链接：https://juejin.cn/post/7030291455243452429