seriska comm javascript

async function initCommand(port, command, commandData) {
    let seq = ' '
    const encoder = new TextEncoder('windows-1251')
    const decoder = new TextDecoder('windows-1251')
    const dataPrefix = `\x01%c%c%c%s\x05%c%c%c%c\x03`
    let data = new Uint8Array(255)
    let data2 = new Uint8Array(255)
    let checkSum = 0
    let len, i, bytwrite, bytread, tries
    let bcc = new Uint8Array(4)

    let commandString = String.fromCharCode(seq, command, ...commandData)
    let dataString = dataPrefix.replace('%c', seq).replace('%c', command).replace('%s', commandData)
    data = encoder.encode(dataString)

    for (len = 1; data[len] !== 0x05; len++) checkSum += data[len]

    len += 32 - 1
    checkSum = checkSum - '%' - 'c' + len + 0x05

    i = (checkSum & 0xf) + 0x30
    bcc[0] = i
    i = ((checkSum & 0xf0) >> 4) + 0x30
    bcc[1] = i
    i = ((checkSum & 0xf00) >> 8) + 0x30
    bcc[2] = i
    i = ((checkSum & 0xf000) >> 12) + 0x30
    bcc[3] = i

    data2 = encoder.encode(dataString.replace('%c', len).replace('%c', bcc[3]).replace('%c', bcc[2]).replace('%c', bcc[1]).replace('%c', bcc[0]))

    if (seq === '#') seq = ' '
    else seq = '#'

    len = data2.length

    const writer = port.writable.getWriter()
    try {
      for (i = 0; i < len; i++) {
        await writer.write(data2.slice(i, i + 1))
      }
    } finally {
      writer.releaseLock()
    }

    await new Promise((resolve) => setTimeout(resolve, 60))

    data = new Uint8Array(255)

    const reader = port.readable.getReader()
    try {
      for (tries = 0; tries < 5; tries++) {
        const { value, done } = await reader.read()
        if (done) break
        if (value[0] === 0x16) {
          tries--
          await new Promise((resolve) => setTimeout(resolve, 60))
        } else if (value[0] === 0x01) {
          len = 1
          while (value[len - 1] !== 0x03) {
            const { value: chunk, done: chunkDone } = await reader.read()
            if (chunkDone) break
            data.set(chunk, len)
            len += chunk.length
          }
          data[len] = 0
          break
        }
      }
    } finally {
      reader.releaseLock()
    }

    if (data[0] === 0) console.log('ERROR: No bytes to read')
    console.log(decoder.decode(data.slice(4)))

    return data
  }



/// POVIKUVANJE NA FUNKCIJATA

const str = '2Е2'
let port
try {
    port = await navigator.serial.requestPort()
    if (port.readable || port.writable) {
        await port.close()
    }
    await port.open({ baudRate: 9600 })

    const lines = str
    .split('\n')
    .map((line) => line.trim())
    .filter((line) => line.length > 0)

    for (const line of lines) {
        await initCommand(port, line[0], line.slice(1))
    }
} catch (error) {
    console.error('ERROR:', error)
    await port.close()
}