fs-- file system文件操作 讀寫文件都是異步操作 ~~~ fs.readFile //readFile(filename,function(err,data){ }) fs.writeFile //writeFile(filename,writeContent,function(err){ }) ~~~ ## 1.fs.readFile ~~~ const fs = require("fs"); fs.readFile('input.txt',(err,data)=>{ if(err){ console.log(err) }else{ console.log(data.toString()) } }) ~~~ ## 2.fs.writeFile ~~~ const fs = require("fs"); fs.writeFile("input.txt","add content",(err)=>{ console.log(err) }) ~~~