const fs = require('fs')
fs.writeFile('a.txt','2222',{flag:'a'},(error)=>{
if(!error){
console.log('文件写入成功')
}
})
//流式写入
let ws = fs.createWriteStream('b.txt',{flags:'a'})
ws.on('open', () => {
console.log('打开流')
})
ws.write('111111\n')
ws.write('22222')
ws.write('333333')
ws.close()
ws.on('close', () => {
console.log('关闭流')
})