之前的文件下载功能一般是由前后端配合实现,由于项目需要,纯前端实现了一把excel的导出功能:
一、excel导出
1.安装依赖库
xlsx:这是一个功能强大的excel处理库,但是上手难度也很大,还涉及不少二进制的东西
file-saver:ES5新增了相关file,blob,fileList等API,但不是所有浏览器都支持,file-saver在没有原生支持saveAs的浏览器上实现了saveAs()接口
script-loader: 在全局上下文环境中执行一次js脚本。
npm install -D xlsx ,file-saver
npm install -s script-loader
二、引入相关依赖
上述部分依赖不支持import引入,所以需要使用'script-loader'将他们挂载到全局环境下;
其中的blob.js是github上的一个开源文件,对于浏览器不能原生支持blob的情况,提供了兼容解决方案,其地址是:https://github.com/eligrey/Blob.js
require('script-loader!file-saver'); //保存文件用 require('script-loader!vendor/Blob'); //转二进制用 require('script-loader!xlsx/dist/xlsx.core.min'); //xlsx核心
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
/* eslint-disable */ /* Blob.js * A Blob implementation. * 2014-05-27 * * By Eli Grey, http://eligrey.com * By Devin Samarin, https://github.com/eboyjr * License: X11/MIT * See LICENSE.md */ /*global self, unescape */ /*jslint bitwise: true, regexp: true, confusion: true, es5: true, vars: true, white: true, plusplus: true */ /*! @source http://purl.eligrey.com/github/Blob.js/blob/master/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(/^[objects(.*)]$/)[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));
三、封装Export2Excel.js,它对外暴露两个接口:export_table_to_excel
和export_json_to_excel
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
/* eslint-disable */ require('script-loader!file-saver'); require('script-loader!./Blob.js'); 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") }
四、调用
handleDownload() { require.ensure([], () => { // 用 webpack Code Splitting xlsl还是很大的 const { export_json_to_excel } = require('vendor/Export2Excel'); const tHeader = ['序号', '文章标题', '作者', '阅读数', '发布时间']; // excel 表格头 const filterVal = ['id', 'title', 'author', 'pageviews', 'display_time']; const list = this.list; const data = this.formatJson(filterVal, list); // 自行洗数据 按序排序的一个array数组 export_json_to_excel(tHeader, data, '列表excel'); }) }, formatJson(filterVal, jsonData) { return jsonData.map(v => filterVal.map(j => v[j])) }
二、csv导出
说实话,如果系统不强制要求excel格式的话,使用csv导出方便太多了,创建一个a标签,写上data:text/csv;charset=utf-8,把数据塞进去,encodeURI(csvContent)就可以了,可以参见自己封装的这个downloadBtn组件
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<template> <a ref="link" class="download-btn" v-on:click="handleClick">导出</a> </template> <script type="text/javascript"> export default { props: { header: { type: Array, default: function() { return []; } }, data: { type: Array, default: function() { return []; } }, fileName: { type: String, default: 'data.csv' } }, methods: { handleClick: function() { if (!this.data || this.data.length <= 0) { this.$message({ message: '请先进行查询,并等待查询结果返回!', type: 'error' }); return; } var csvContent = 'data:text/csv;charset=utf-8,ufeff'; csvContent += this.headerLabel + ' '; this.data.forEach((item, index) => { let dataString = ''; for (let i = 0; i < this.headerProp.length; i++) { dataString += item[this.headerProp[i]] + ','; } csvContent += index < this.data.length ? dataString.replace(/,$/, ' ') : dataString.replace(/,$/, ''); }); this.$refs.link.setAttribute('href', encodeURI(csvContent)); this.$refs.link.setAttribute('download', this.fileName); } }, computed: { // 要求head是数组,数组中的每个元素是对象,并且每个对象都有label属性 headerLabel: function() { let result; result = this.header.map((item) => { return item.label; }) result = result.join(','); return result; }, headerProp: function() { let result; result = this.header.map((item) => { return item.prop; }) return result; } } } </script> <style lang="scss" scoped> .download-btn { display: inline-block; margin-left: 10px; padding: 2px 15px; font-size: 12px; border-radius: 4px; color: #FFF; background-color: #f7ba2a; border-color: #f7ba2a; outline: 0; text-align: center; -webkit-appearence: none; appearence: none; cursor: pointer; } </style>