RemoveSemicolonsBasedOnEslint.js

const fs = require('fs')

const getLog = () => {
  return new Promise((done, reject) => {
    fs.readFile('./semi.log', { encoding: 'utf-8' }, (err, data) => {
      err
        ? reject(err)
        : done(data)
    })
  })
}

const parseLog = log => {
  const blocks = getBlocks(log)
  return blocks
}

const getBlocks = log => log.split(/^$/m).map(parseBlock)

const parseBlock = block => {
  const [file, ...errors] = block.split('\n').filter(line => !!line)
  return { file, errors }
}

const fixSemicolons = block => {
  const semicolonErrors = block.errors
    .filter(error => error.includes('Extra semicolon  semi'))

  return readFile(block.file)
    .then(fileContent => {
      return semicolonErrors.reduce(
        (newFileContent, error) => (
          removeSemicolon(error, newFileContent)
        ), fileContent)
    })
    .then(newFileContent => {
      writeFile(block.file, newFileContent)
    })
}

const readFile = file => {
  return new Promise((done, reject) => {
    fs.readFile(file, { encoding: 'utf-8' }, (err, data) => {
      err ? reject(err) : done(data)
    })
  })
}

const writeFile = (file, content) => {
  return new Promise((done, reject) => {
    fs.writeFile(file, content, { encoding: 'utf-8' }, err => {
      err ? reject(err) : done()
    })
  })
}

const removeSemicolon = (error, fileContent) => {
  const [, row, column] = error.match(/(\d+):(\d+)/)
  const rows = fileContent.split('\n')
  rows[row - 1] = rows[row - 1].slice(0, column - 1) + rows[row - 1].slice(column)
  return rows.join('\n')
}

getLog()
  .then(parseLog)
  .then(blocks => blocks.forEach(fixSemicolons))
  .then(console.log)
  .catch(console.err)