Use a stream to parse data

streamReader.js

import fs from 'fs'
import Stream from 'stream'
import { StringDecoder } from 'string_decoder'
import through from 'through2'

const string = `
Bright Black	90	100	85,85,85	128,128,128	128,128,128	129,131,131	85,85,85	127,127,127	127,127,127		128,128,128
Bright Red	91	101	255,85,85	255,0,0	255,0,0	252,57,31	255,85,85	255,0,0	255,0,0		255,0,0
`

const decoder = new StringDecoder('utf8')

const split = () => {
  function parser(rs: Stream.Transform | Stream.Readable, buffer: Buffer) {
    const decoded = decoder.write(buffer)
    const splited = decoded.split('\n').map(e => e.split('\t', 3))

    for (let i of splited) {
      for (let k of i) {
        // rs.setEncoding('utf-8')
        rs.push(k)
      }
    }
    console.log('splited : ', splited)
  }

  return through.obj(function(buffer: Buffer, enc, done) {
    parser(this, buffer)
    done()
  })
}

let i = 0
fs.createReadStream('./test.txt')
  .pipe(split())
  .on('data', function(buffer) {
    console.log(`${i++} ✅ buffer : `, buffer)
  })
  .on('finish', () => console.log('🌈 Finished !'))

const rs = new Stream.Readable()
i = 0
rs._read = () => {
  console.log('😄 It is started reading')
}
rs.push(string)
// rs.push(null)
rs.pipe(split())
  .on('data', function(buffer) {
    console.log(`${i++} ❌ buffer : `, buffer)
  })
  .on('finish', () => console.log('🌈 Finished !'))
rs.read()


// 😄 It is started reading
// 0 ❌ buffer :
// 1 ❌ buffer :  Bright Black
// 2 ❌ buffer :  90
// 3 ❌ buffer :  100
// 4 ❌ buffer :  Bright Red
// 5 ❌ buffer :  91
// 6 ❌ buffer :  101
// 7 ❌ buffer :
// splited :  [ [ '' ],
//   [ 'Bright Black', '90', '100' ],
//   [ 'Bright Red', '91', '101' ],
//   [ '' ] ]
// 8 ✅ buffer :  Bright Black
// 9 ✅ buffer :  90
// 10 ✅ buffer :  100
// 11 ✅ buffer :  Bright Red
// 12 ✅ buffer :  91
// 13 ✅ buffer :  101
// splited :  [ [ 'Bright Black', '90', '100' ],
//   [ 'Bright Red', '91', '101' ] ]
// 🌈 Finished !

streamReader2.js

import fs from 'fs'
import Stream from 'stream'
import { StringDecoder } from 'string_decoder'
import through from 'through2'

const string = `
Black	30	40	0,0,0	1,1,1
Red	31	41	170,0,0	128,0,0	128,0,0	194,54,33	187,0,0	127,0,0	205,0,0	255,0,0	222,56,43
Green	32	42	0,170,0	0,128,0	0,128,0	37,188,36	0,187,0	0,147,0	0,205,0	0,255,0	57,181,74
Yellow	33	43	170,85,0[nb 6]	128,128,0	238,237,240	173,173,39	187,187,0	252,127,0	205,205,0	255,255,0	255,199,6
Blue	34	44	0,0,170	0,0,128	0,0,128	73,46,225	0,0,187	0,0,127	0,0,238[23]	0,0,255	0,111,184
Magenta	35	45	170,0,170	128,0,128	1,36,86	211,56,211	187,0,187	156,0,156	205,0,205	255,0,255	118,38,113
Cyan	36	46	0,170,170	0,128,128	0,128,128	51,187,200	0,187,187	0,147,147	0,205,205	0,255,255	44,181,233
White	37	47	170,170,170	192,192,192	192,192,192	203,204,205	187,187,187	210,210,210	229,229,229	255,255,255	204,204,204
Bright Black	90	100	85,85,85	128,128,128	128,128,128	129,131,131	85,85,85	127,127,127	127,127,127		128,128,128
Bright Red	91	101	255,85,85	255,0,0	255,0,0	252,57,31	255,85,85	255,0,0	255,0,0		255,0,0
Bright Green	92	102	85,255,85	0,255,0	0,255,0	49,231,34	85,255,85	0,252,0	0,255,0	144,238,144	0,255,0
Bright Yellow	93	103	255,255,85	255,255,0	255,255,0	234,236,35	255,255,85	255,255,0	255,255,0	255,255,224	255,255,0
Bright Blue	94	104	85,85,255	0,0,255	0,0,255	88,51,255	85,85,255	0,0,252	92,92,255[24]	173,216,230	0,0,255
Bright Magenta	95	105	255,85,255	255,0,255	255,0,255	249,53,248	255,85,255	255,0,255	255,0,255		255,0,255
Bright Cyan	96	106	85,255,255	0,255,255	0,255,255	20,240,240	85,255,255	0,255,255	0,255,255	224,255,255	0,255,255
Bright White	97	107	255,255,255	255,255,255	255,255,255	233,235,235	255,255,255	255,255,255	255,255,255	
`

const decoder = new StringDecoder('utf8')

const split = () => {
  function parser(rs: Stream.Transform | Stream.Readable, buffer: Buffer) {
    const decoded = decoder.write(buffer)
    const splited = decoded.split('\n').map(e => e.split('\t', 3))

    for (let i of splited) {
      for (let k of i) {
        // rs.setEncoding('utf-8')
        if (k === '') continue
        if (k.indexOf(' ') > 0) {
          k = k.split(' ').join('')
        }
        rs.push(k)
      }
    }
    // console.log('splited : ', splited)
  }

  return through.obj(function(buffer: Buffer, enc, done) {
    parser(this, buffer)
    done()
  })
}

let i = 0
// fs.createReadStream('./test.txt')
//   .pipe(split())
//   .on('data', function(buffer) {
//     console.log(`${i++} ✅ buffer : `, buffer)
//   })
//   .on('finish', () => console.log('🌈 Finished !'))

const rs = new Stream.Readable()
i = 0
let FgStr = '',
  BgStr = '',
  tmp = []
rs._read = () => {
  console.log('😄 It is started reading')
}
rs.push(string)
rs.push(null)
const ws = fs.createWriteStream('./a.txt')
rs.pipe(split())
  .on('data', function(buffer) {
    if (i === 2) {
      FgStr += `Fg${tmp[0]} = '\\x1b[${tmp[1]}m'\n`
      BgStr += `Bg${tmp[0]} = '\\x1b[${buffer}m'\n`
      tmp = []
    } else {
      tmp.push(buffer)
    }
    // console.log(`${i++} ❌ buffer : `, buffer)
    i++
    i %= 3
    // console.log(i)
  })
  .on('finish', () => {
    console.log('🌈 Finished !')

    ws.write(FgStr)
    ws.write('\n\n')
    ws.write(BgStr)
  })

rs.read()


// FgBlack = '\x1b[30m'
// FgRed = '\x1b[31m'
// FgGreen = '\x1b[32m'
// FgYellow = '\x1b[33m'
// FgBlue = '\x1b[34m'
// FgMagenta = '\x1b[35m'
// FgCyan = '\x1b[36m'
// FgWhite = '\x1b[37m'
// FgBrightBlack = '\x1b[90m'
// FgBrightRed = '\x1b[91m'
// FgBrightGreen = '\x1b[92m'
// FgBrightYellow = '\x1b[93m'
// FgBrightBlue = '\x1b[94m'
// FgBrightMagenta = '\x1b[95m'
// FgBrightCyan = '\x1b[96m'
// FgBrightWhite = '\x1b[97m'

// BgBlack = '\x1b[40m'
// BgRed = '\x1b[41m'
// BgGreen = '\x1b[42m'
// BgYellow = '\x1b[43m'
// BgBlue = '\x1b[44m'
// BgMagenta = '\x1b[45m'
// BgCyan = '\x1b[46m'
// BgWhite = '\x1b[47m'
// BgBrightBlack = '\x1b[100m'
// BgBrightRed = '\x1b[101m'
// BgBrightGreen = '\x1b[102m'
// BgBrightYellow = '\x1b[103m'
// BgBrightBlue = '\x1b[104m'
// BgBrightMagenta = '\x1b[105m'
// BgBrightCyan = '\x1b[106m'
// BgBrightWhite = '\x1b[107m'