Skip to content

File related

Browser Download

Handle Blob/ file saving in browser

// Ref from https://medium.com/@fakiolinho/handle-blobs-requests-with-axios-the-right-way-bb905bdb1c04

// In fileSave.js
import FileSaver from 'file-saver';

export default (fileData, fileName) => FileSaver.saveAs(fileData, fileName);

// In <any API functions>.js
import fileSaver from './fileSaver';
import moment from "moment"

export async function downloadFile() {
    const blobData = await someApiRequest()
    const zip_file_name = moment().format("YYYYMMDD-hhmmss") + ".zip"
    await fileSaver(ran_res, zip_file_name);
}

File Create/Read/Delete

Write file

const fs = require('fs');

const content = 'Some content!'

try {
  fs.writeFileSync('/Users/joe/test.txt', content)
  // file written successfully
} catch (err) {
  console.error(err)
}

Read File

const fs = require('fs')

css = fs.readFileSync(CSS_FILE_PATH, 'utf8')

Create directory

const fs = require('fs')

fs.mkdirSync("xxxx/xxxx")

Remove directory

const fs = require('fs')

fs.rmSync(dir_path, { recursive: true })

const fs = require('fs')

fs.symlinkSync(src_path, link_path, 'dir')

const fs = require('fs')

fs.unlinkSync(link_path)

CSV file

Libs:

Example of reading a CSV ( with Papaparse )

const Papa = require("papaparse")
const fs = require("fs")

// file path
let path = "/xxxx.csv"

// This is async way to read
function asyncWay() {
  let config = {
    complete: function(results, file) {
      console.log("Parsing complete:");
      console.log(results);
      console.log("-------------------")
      console.log(file);
    }
  }
  // Async here !!
  Papa.parse(
    fs.createReadStream(path),
    config)
}

// This is sync way
function syncWay(){
  const csv_str = fs.readFileSync(path, "utf8")
  const csvobj = Papa.parse(csv_str)  
  console.log(csvobj)
}

//asyncWay()
syncWay()

/* The result object looks like this
{
  data: [
    [ 'col_a', 'col_b', 'col_c' ],
    [
      '株式会社クリーク・アンド・リバー社',
      'CREEK & RIVER Co.,Ltd.',
      'カブシキガイシャクリークアンドリバーシャ'
    ],
    [ '' ]
  ],
  errors: [],
  meta: {
    delimiter: ',',
    linebreak: '\r\n',
    aborted: false,
    truncated: false,
    cursor: 84
  }
}
*/

Path Manipulation

Check path exist

const fs = require('fs')

if (!fs.existsSync(entry_server_path)) {
    console.log("Not existed!")
}

Path string concat

const path = require("path")

path.join(__dirname, "../something.js")

Path resolve

const path = require("path")

path.resolve(path.join(dist_path, '/entry-server.css'))

Get the most-right file name

const path = require("path")

console.log(path.basename("/home/user/abc/def/tttt.txt"))
// tttt.txt

Get the dir name

const path = require("path")

console.log(path.dirname("/home/user/abc/def/tttt.txt"))
// /home/user/abc/def
console.log(path.dirname("../abc/def/tttt.txt"))
// ../abc/def

Zip File

Using lib: https://www.archiverjs.com/docs/quickstart

  • Zip some files: (In NodeJS)
> DO NOT rely on `archive.finalize()`, you should resolve in the “close/end” listener
>

```jsx
// require modules
const fs = require('fs');
const archiver = require('archiver');

// create a file to stream archive data to.
const output = fs.createWriteStream(__dirname + '/example.zip');
const archive = archiver('zip', {
  zlib: { level: 9 } // Sets the compression level.
});

// listen for all archive data to be written
// 'close' event is fired only when a file descriptor is involved
output.on('close', function() {
  console.log(archive.pointer() + ' total bytes');
  console.log('archiver has been finalized and the output file descriptor has closed.');
});

// This event is fired when the data source is drained no matter what was the data source.
// It is not part of this library but rather from the NodeJS Stream API.
// @see: https://nodejs.org/api/stream.html#stream_event_end
output.on('end', function() {
  console.log('Data has been drained');
});

// good practice to catch warnings (ie stat failures and other non-blocking errors)
archive.on('warning', function(err) {
  if (err.code === 'ENOENT') {
    // log warning
  } else {
    // throw error
    throw err;
  }
});

// good practice to catch this error explicitly
archive.on('error', function(err) {
  throw err;
});

// pipe archive data to the file
archive.pipe(output);

// append a file from stream
const file1 = __dirname + '/file1.txt';
archive.append(fs.createReadStream(file1), { name: 'file1.txt' });

// append a file from string
archive.append('string cheese!', { name: 'file2.txt' });

// append a file from buffer
const buffer3 = Buffer.from('buff it!');
archive.append(buffer3, { name: 'file3.txt' });

// append a file
archive.file('file1.txt', { name: 'file4.txt' });

// append files from a sub-directory and naming it `new-subdir` within the archive
archive.directory('subdir/', 'new-subdir');

// append files from a sub-directory, putting its contents at the root of archive
archive.directory('subdir/', false);

// append files from a glob pattern
archive.glob('file*.txt', {cwd:__dirname});

// finalize the archive (ie we are done appending files but streams have to finish yet)
// 'close', 'end' or 'finish' may be fired right after calling this method so register to them beforehand
archive.finalize();
```

Comments