node.js & fs & file read & file write

const fs = require("fs");// absolute pathfs.open("/open/some/file.txt", "r", (err, fd) => {    if (err) {        throw err;    }    fs.close(fd, (err) => {        if (err) {            throw err;        }    });});// relative pathfs.open("file.txt", "r", (err, fd) => {    if (err) {        throw err;    }    fs.close(fd, (err) => {        if (err) {            throw err;        }    });});

readline

const readline = require('readline');const rl = readline.createInterface({    input: process.stdin,    output: process.stdout});rl.question('What do you think of Node.js? ', (answer) => {  // TODO: Log the answer in a database  console.log(`Thank you for your valuable feedback: ${answer}`);  rl.close();});

const fs = require("fs");const readline = require('readline');const rl = readline.createInterface({    input: process.stdin,    output: process.stdout});// absolute path// fs.open("/open/some/file.txt", "r", (err, fd) => {//     if (err) {//         throw err;//     }//     fs.close(fd, (err) => {//         if (err) {//             throw err;//         }//     });// });// relative pathfs.open("file.txt", "r", (err, fd) => {    if (err) {        throw err;    }    console.log(`fd =`, fd);// 3    rl.on('line', (fd) => {    console.log(`Received: ${fd}`);    });    fs.close(fd, (err) => {        if (err) {            throw err;        }    });});

bug

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write & read

// preview.jsconst fs = require("fs");const readline = require("readline");fs.writeFile("file.js", `export const APP_ENV = "preview";`, function(err) {    if(err) {        console.log(err);        return err;    }    let env = "preview";    console.log("The file was saved!", env);});let rd = readline.createInterface({    input: fs.createReadStream("file.js"),    output: process.stdout,    console: false});rd.on("line", function(line) {    console.log(`line =`, line);});// fs.writeFile("file.txt", "prview", function(err) {//     if(err) {//         console.log(err);//         return err;//     }//     console.log("The file was saved!");// });// global.APP_ENV = "testing";// let APP_ENV = global.APP_ENV;// console.log(`APP_ENV =`, APP_ENV);// let rd = readline.createInterface({//     input: fs.createReadStream('file.txt'),//     output: process.stdout,//     console: false// });// rd.on('line', function(line) {//     console.log(`line =`, line);// });

// testing.jsconst fs = require("fs");const readline = require("readline");fs.writeFile("file.js", `export const APP_ENV = "testing";`, function(err) {    if(err) {        console.log(err);        return err;    }    let env = "testing";    console.log("The file was saved!", env);});// const rl = readline.createInterface({//     input: process.stdin,//     output: process.stdout// });// absolute path// fs.open("/open/some/file.txt", "r", (err, fd) => {//     if (err) {//         throw err;//     }//     fs.close(fd, (err) => {//         if (err) {//             throw err;//         }//     });// });// global.APP_ENV = "testing";// let APP_ENV = global.APP_ENV;// console.log(`APP_ENV =`, APP_ENV);// relative path// fs.open("file.js", "r", (err, fd) => {//     if (err) {//         throw err;//     }//     console.log(`fd =`, fd);// 3//     fs.close(fd, (err) => {//         if (err) {//             throw err;//         }//     });// });let rd = readline.createInterface({    input: fs.createReadStream("file.js"),    output: process.stdout,    console: false});rd.on("line", function(line) {    console.log(`line =`, line);});

// file.jsexport const APP_ENV = "testing";

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global var

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