前沿

最近再写vue-element-ui-pc项目中需要把数据导出为excel的需求，于是乎就开始折腾呗，没办法，谁让之前没有写过vue的导出数据呢，不折腾的攻城狮跟病猫有什么区别，不多说了，上思路与代码。

好在折腾了两天发现了js-xlsx这个东东，一个功能很强大excel处理库，只是下载各种格式excel，还支持读取excel，于是我就借鉴官网的例子搞了一下，其实原理我也不太懂，只是在使用造好的轮子而已。

写在开始，在本插件中需要注意到的几个地方

以下为需要用到的插件库
npm install file-saver@1.3.3     用来保存文件的
npm install --save-dev script-loader   由于由于这几个文件不支持import引入，所以我们需要`script-loader`来将他们挂载到全局环境下。
npm install xlsx   //就是上边提到的js-xlsx这个东东
npm install jszip  //导出为压缩文件////或者是将文件压缩

Step 一

首先，先创建一个公共文件夹，里边存放封装的公共的导出的js,这里起名为vendor,里边放三个封装好的文件，分别为

1，Blog.js

//Blog.js官网写好的，直接用就好了，主要是用来转二进制用的。
/* eslint-disable */
(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));

2，Export2Excel.js

//主要是处理好数据并且暴露了两个接口export_table_to_excel和export_json_to_excel,我们常用export_json_to_excel因为更加的可控一点，我们可以自由的洗数据。
/* eslint-disable */
require('script-loader!file-saver');
require('script-loader!@/vendor/Blob');
import XLSX from 'xlsx'

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);
    var oo = generateArray(theTable);
    var ranges = oo[1];

    /* original data */
    var data = oo[0];
    var ws_name = "SheetJS";

    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")
}

export function export_json_to_excel({ header, data, filename = 'excel-list', autoWidth = true } = {}) {
    /* original data */
    data = [...data]
    data.unshift(header);
    var ws_name = "SheetJS";
    var wb = new Workbook(),
        ws = sheet_from_array_of_arrays(data);

    if (autoWidth) {
        /*设置worksheet每列的最大宽度*/
        const colWidth = data.map(row => row.map(val => {
                /*先判断是否为null/undefined*/
                if (val == null) {
                    return { 'wch': 10 };
                }
                /*再判断是否为中文*/
                else if (val.toString().charCodeAt(0) > 255) {
                    return { 'wch': val.toString().length * 2 };
                } else {
                    return { 'wch': val.toString().length };
                }
            }))
            /*以第一行为初始值*/
        let result = colWidth[0];
        for (let i = 1; i < colWidth.length; i++) {
            for (let j = 0; j < colWidth[i].length; j++) {
                if (result[j]['wch'] < colWidth[i][j]['wch']) {
                    result[j]['wch'] = colWidth[i][j]['wch'];
                }
            }
        }
        ws['!cols'] = result;
    }

    /* 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" }), filename + ".xlsx");
}

2，Export2Zip.js

//暴漏出export_txt_to_zip这个接口，用来到处压缩文件的
/* eslint-disable */
require('script-loader!file-saver');
import JSZip from 'jszip'

export function export_txt_to_zip(th, jsonData, txtName, zipName) {
  const zip = new JSZip()
  const txt_name = txtName || 'file'
  const zip_name = zipName || 'file'
  const data = jsonData
  let txtData = `${th}\r\n`
  data.forEach((row) => {
    let tempStr = ''
    tempStr = row.toString()
    txtData += `${tempStr}\r\n`
  })
  zip.file(`${txt_name}.txt`, txtData)
  zip.generateAsync({type:"blob"}).then((blob) => {
    saveAs(blob, `${zip_name}.zip`)
  }, (err) => {
    alert('导出失败')
  })
}

接下来就是在页面中使用了

  <el-button type="warning"
                     style="width:100px;height:36px;"
                     ref="btn"
                     @click='ExportData'>导出数据</el-button>
<script>
export default {
  data() {
    return {
           list: [
        {
          author: "Carol",
          comment_disabled: true,
          content_short: "我是测试数据",
          display_time: "1974-06-19 10:01:57",
          forecast: 71.85,
          id: 1,
          importance: 2,
          pageviews: 1670,
          reviewer: "Ruth",
          status: "deleted",
          timestamp: 1126391703464,
          title: "哦i啥v就开始对方能看出来市场v恐龙世界",
          type: "JP"
        }
      ],
      listLoading: true,
      downloadLoading: false,
      filename: "",
      autoWidth: true
    };
  },
  methods: {
    ExportData() {
      console.log("导出数据");
      import("@/vendor/Export2Excel").then(excel => {
  //表格的表头列表
        const tHeader = ["Id", "Title", "Author", "Readings", "Date"];
//与表头相对应的数据里边的字段
        const filterVal = [
          "id",
          "title",
          "author",
          "pageviews",
          "display_time"
        ];
        const list = this.list;
        const data = this.formatJson(filterVal, list);
   //这里还是使用export_json_to_excel方法比较好，方便操作数据
        excel.export_json_to_excel({
          header: tHeader,
          data,
          filename: this.filename,
          autoWidth: this.autoWidth
        });
        this.downloadLoading = false;
      });
    },
//洗数据
    formatJson(filterVal, jsonData) {
      return jsonData.map(v =>
        filterVal.map(j => {
          // if (j === "timestamp") {
            // return parseTime(v[j]);
          // } else {
            return v[j];
          // }
        })
      );
},
  }
};
</script>

结束语

至此，vue的到处excel就搞好了，其他两个，本次没有写demo,后期更新时会更新。还是那句话遇到需求，要迎接需求，折腾几次就好了。将本次折腾的结果记录下来，方便自己总结也希望可以帮助到小伙伴们。
要用公共组件请看更新的vue-xlsx 导出数据公共组件