How to filter by a column in exceljs with Javascript before transcribing results to Google Sheets API via Node

Question

I have written a script which uses the following:

// https://nodejs.org/
// https://developers.google.com/sheets/api/quickstart/nodejs?hl=en
// npm install googleapis@39 --save
// https://www.npmjs.com/package/exceljs

I need to somehow map or filter results to end up with all rows in a variable which contains "WN" in the 11th column (which contains the region of the results or that row).

The script reads a CSV sheet into a variable called "data" in an async function:

const worksheet = await wb.csv.readFile(CSVFileName, options);
      // ... use workbook or worksheet

    let data = worksheet.getSheetValues(); 
    data = data.map(function(r){
       return [r[1],r[2],r[4],r[11],r[13],r[15],r[16],r[54],r[56]];  
         // filter should be applied here: if r[11] = "WN"

I have tried to apply a filter, but I struggle working with the data as it is an "array inside and array inside an array" so to say:

let data2 = data.filter(function(region){
  if (region.data = "WN") {
    return true;
  }    
});

The code as it is doesn't filter correctly and returns the following, in stead of filtering by the 4'th item in the array. See items other than "WN" in the array below:

[
    'AA05299040',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299041',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'P',
    data: 'WN'
  ],
  [
    'AA05299042',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299043',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299044',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299045',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299047',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299048',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299051',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299055',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299058',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299059',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299060',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299061',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299062',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'P',
    data: 'WN'
  ],
  [
    'AA05299063',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299064',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299066',
    '08/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299526',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299528',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299530',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299531',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299532',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299533',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299534',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299535',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299538',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299542',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  [
    'AA05299549',
    '09/07/2020',
    '09/07/2020',
    'KN',
    'AA',
    '41I006',
    'Inkosi Albert Luthuli Hospital',
    '09/07/2020',
    'N',
    data: 'WN'
  ],
  ... 15362 more items
]

I've also tried this: which gives an error:

let data2 = data.filter(function(region){
      if (region.data.r[4] = "WN") {
        return true;
      }

(node:16260) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'r' of undefined

score 0 · Answer 1 · answered Nov 27 '20 at 06:09

Use the strict equality operator instead of the assignment operator inside the if statement.

It is advisable to not use simple assignments in a conditional expression, because the assignment can be confused with equality when glancing over the code. - MDN

How to filter by a column in exceljs with Javascript before transcribing results to Google Sheets API via Node

1 Answers1