Nodejs file operation

This article will introduce nodejs Some operations of reading and writing local files .

Reading documents

const fs = require('fs')
const path = require('path')

const fileName = path.resolve(__dirname, 'data.txt')

console.log(fileName)
//  Reading documents 
fs.readFile(fileName, (err, data) => {
  if (err) {
    console.log(err)
    return
  }
  // data  It's a binary type , Need to be converted to a string 
  console.log('readFile',data.toString())
})

Writing documents

const content = ' What to write '
const opt = {
  flag:'a' //  Append mode 
}
fs.writeFile(fileName, content, opt, (err) => {
  if (err) {
    console.log(err)
  }
})

Judge whether the file exists

fs.exists(fileName, (exist) => {
  console.log('exits',exist)
})