# NodeJsBeginner

**Repository Path**: baizhi958216/node-js-beginner

## Basic Information

- **Project Name**: NodeJsBeginner
- **Description**: https://channel9.msdn.com/Series/Beginners-Series-to-JavaScript/Beginning-the-Beginners-series-1-of-51
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 1
- **Forks**: 0
- **Created**: 2022-01-31
- **Last Updated**: 2022-07-01

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

```javascript
function reS(resValue) {
    let resdValue = "";
    resValue.split("").forEach((char) => {
        resdValue = char + resdValue;
    });
    return resdValue;
}

console.log(reS("hi"));

var hello = "hello";
console.log(hello);

hello = "Hello World";
console.log(hello);

if (1) {
    let world = "HelloWorld";
    console.log(world);
}

const cyan = "cyans";
console.log(cyan);
cyan = "new cyans"

let str1 = "Hello ";
let str2 = "World";
console.log(str1 + str2);
console.log(str1 + "Big " + str2);

let num1 = 1;
let num2 = "5";
console.log(num1 + num2);
console.log(num1 + 1);

let str1 = "JavaScript";
let str2 = "fun";
console.log(`I am writing code in ${str1}.`);
console.log(`Formatting in ${str1} is ${str2}.`);

let boolean1 = true;

console.log(`1 + 1 is ${1+1}.`);
console.log(`The opposite of true is ${!boolean1}!1`);

let str = 'true';
console.log(typeof(str));

let str1 = 0 == ''; //type coerced, only 0 equals to true
let str2 = 'abc' === 'abc'; //type respected
console.log(str2);

const people = ["John", "Lisa", "Peter"];
const one = new Number(1);
const str = "Hello World";
const b = true;
const person = {
    firstName: "Linus",
    lastName: "Torvalds"
};

function sayHello(person) {
    console.log("Hello " + person.firstName);
}
console.log("------type of------");
console.log(typeof(people)); //object
console.log(typeof(one));
console.log(typeof(str));
console.log(typeof(b));
console.log(typeof(person));
console.log(typeof(sayHello));

console.log("------instanceof------");
console.log(people instanceof Array);
console.log(one instanceof Number);
console.log(str instanceof String);
console.log(b instanceof Boolean);
console.log(person instanceof Object);
console.log(sayHello instanceof Function);

let num1 = 300;
console.log(Math.PI);
console.log(Math.sqrt(num1)); //Square root
console.log(num1 + 100);
console.log(num1 - 100);
console.log(num1 * 100);
console.log(num1 / 100);
console.log(++num1); //Increment
console.log(--num1); //Decrement

const num1 = '150';
console.log(parseInt('1.5'));
console.log(parseInt(num1));
console.log(parseInt('Hello'));
console.log(parseInt('0xA')); //Hexadecimal number

console.log(parseFloat('1.5'));
console.log(parseInt(`${1+1}`));

const num2 = 114.514;
console.log(num2.toString());
console.log((0xf).toString());

throw 'myException';
throw true;

try {
    // criticalCode();
    throw "Error throwed"
} catch (ex) {
    console.log("Got an error!");
    logError(ex);
} finally {
    console.log("Finally will run always!");
}

function criticalCode() {
    throw "throwing an exception";
    // console.log("Hello,There is no error");
}

function logError(theException) {
    console.log(theException);
}
console.log("\n**********Throwing Exceptions*********\n");
throw 'myException';
throw true;

// Try...Catch
console.log("\n**********Try...Catch*********\n");
try {
    criticalCode();
} catch (ex) {
    console.log("Got an error");
    logError(ex);
}

// Throwing in Try..Catch
console.log("\n*********Throwing in Try..Catch*******\n");
try {
    throw "An exception that is thrown every time";
} catch (ex) {
    console.log("Got an error");
    logError(ex);
}

// Try..Catch..Finally
console.log("\n*********Try..Catch..Finally*******\n");
try {
    throw "An exception that is thrown every time";
} catch (ex) {
    console.log("Got an error");
    logError(ex);
} finally {
    console.log("Code that always will run");
}

// Start at 1970.01.01
const now = new Date();
now.setFullYear(2022);
now.setMonth(0);
now.setDate(28);
now.setHours(17);
now.setMinutes(17);
now.setSeconds(59);
console.log(now);
console.log(`Day of Week :${now.getDay()}`);
console.log(`Date :${now.getDate()}`);
console.log(now.getTime()); //Since 1970.01.01 to now with millionsecond
console.log(now.getFullYear());

const randomDate = new Date(2022, 0, 28, 17, 28, 20); //2020.01.28 17:28:20
const win95Launch = new Date(1995, 7, 24);
console.log(randomDate);
console.log(win95Launch);

const status1 = 400;
if (status1 == 200) {
    console.log("OK!")
}
// ===
if (status1 === 200) {
    console.log('OK!');
} else if (status1 === 400) {
    console.log('Error');
} else {
    console.log('Unknown status');
}
// if-ternary
const statv = 400;
let message = '';
if (statv === 200) {
    message = 'OK!';
} else {
    message = 'Error!';
}
const message = (statv === 200) ? 'OK!' : 'Error!';
console.log(message);

const namee = '';
if (!namee) {
    console.log('No name');
} else {
    console.log('We have a name!');
}

const namee = 'error';
if (namee.toLocaleUpperCase() === 'ERROR') {
    console.log('Something went wrong');
} else {
    console.log('Looks great');
}

const statuss = 200;
if (statuss === 200) {
    console.log('OK!');
} else if (statuss === 400 || statuss === 500) {
    console.log('Error!');
} else {
    console.log('Unknown Status');
}

const statuss = 401;
switch (statuss) {
    case 200:
        console.log('OK!');
        break;
    case 400: //or
    case 500: //or
        console.log('Error');
        break;
    default: //else
        console.log('Unknown Status');
        break;
}

let arrayLength = 5;
let arr1 = [];
let arr2 = Array(arrayLength);
console.log(arr1.length);
console.log(arr2.length);
arr2[3] = 'This is value';
console.log(arr2[3]);
console.log(arr2[arr2.length - 2]);

let arr1 = [1, 2, 3, 4, 5, 6, 7, 8, 9];
let arr2 = ['Hello', 'Hi', 'Bye', 'GoodBye'];
let arr3 = arr1.concat(arr2);
console.log(arr3);
console.log(arr1.push('New Value'));
arr1.unshift('New Value');
console.log(arr1);
console.log(arr1.pop());
arr1.shift();
arr1.shift();
arr1.shift();
console.log(arr1);

let arr1 = ['1', '2', '3', '4'];
let index = 0;
while (index < arr1.length) {
    console.log(arr1[index]);
    index++;
}
for (let index = 0; index < arr1.length; index++) {
    console.log(arr1[index]);
}
for (const index of arr1) {
    console.log(arr1[index - 1]);
}

let arr1 = [];
arr1.push(1);
arr1.push(2);
arr1.pop();
arr1.push(3);
let arr2 = [];
const arr2 = ['hi', 'hello', 1, 2, 3, 1.5]
arr2.unshift(3);
arr2.unshift(2);
arr2.shift();
arr2.unshift(1);
let arr3 = arr1.concat(arr2);
console.log(arr1);
console.log(arr2);
console.log("=========for..in===========");
for (const i in arr2) {
    console.log(typeof(arr2[i]));
}
console.log("=========for..of===========");
for (const i of arr2) {
    console.log(typeof(i));
}
console.log("=========forEach===========");
arr2.forEach(function(i, j) {
    console.log(typeof(i));
})
console.log("=========for===========");
for (let i = 0; i < arr2.length; i++) {
    console.log(typeof(arr2[i]));
}
console.log(arr3);

1.Function Definition
function printHello(name) {
    console.log("Hello！！" + name);
    return name + "!! hello";
}
console.log(typeof(printHello))
let result = printHello("Microsoft");
console.log(result);
function Hi - World() {}

fat arrow function
cl = () => console.log("Hello");
cl()
const add = (a, b) => a + b;
console.log(add(1, 2))

const subtract = (a, b) => {
    const result = a - b;
    return result;
}
console.log(subtract(1, 1));

JSON
const book = new Object({ title: "1984", author: "George Orwell" });
console.log("\n ------ ");
console.log(typeof book);
console.log(book);
const myBooks = [
    new Object({
        title: "1984",
        author: "George Orwell"
    }),
    new Object({
        title: "Becoming",
        author: "Michelle Obama"
    }),
    new Object({
        title: "Snow Crash",
        author: "Neal Stephenson"
    }),
    new Object({
        title: "Predictably Irrational",
        author: "Dan"
    })
];
console.log("\n----------");
console.log(typeof myBooks);
console.log(myBooks);
对象
console.log("\n-----------");
let bookJSON = JSON.stringify(book);
console.log(typeof bookJSON);
console.log(bookJSON);
集合
console.log("\n-----------");
let myBooksJSON = JSON.stringify(myBooks);
console.log(typeof myBooksJSON);
console.log(myBooksJSON);
对象parsed
let data = bookJSON;
let parsed = JSON.parse(data);
console.log(typeof parsed);
console.log(parsed);
console.log(Array.isArray(parsed));
console.log("Num items:" + parsed.length);
集合parsed
data = myBooksJSON
parsed = JSON.parse(data)
console.log(typeof parsed);
console.log(parsed);
console.log(Array.isArray(parsed));
console.log("Num items" + parsed.length);
console.log("Author of 2nd Book:" + parsed[1].author);

const book = new Object();
book.title = "1984";
book.author = "George Orwell";
book.isAvailable = true;
book.checkIn = function() {
    this.isAvailable = true;
    return this;
};
book.checkOut = function() {
    this.isAvailable = false;
    return this;
};
// console.log(typeof book);
console.log(book.title);
// console.log(book['title']);
const book = {
    title: "1984",
    author: "George Orwell",
    isAvailable: true,
    checkIn: function() {
        this.isAvailable = true;
    },
    checkOut: function() {
        this.isAvailable = false;
    }
}
const data = { title: "1984", author: "George Orwell" };
const book = new Object(data);
const bookFun = {
    title: "1984",
    author: "George Orwell",
    isAvailable: true,
    checkIn: function() {
        this.isAvailable = true;
    },
    checkOut: function() {
        this.isAvailable = false;
    }
};
const book = new Object(bookFun);
bookFun.checkOut();
book["checkIn"]();
console.log(book.isAvailable);
console.log(book.author);
book.author = "G. Orwell";
book["author"] = "George Orwell";
console.log(bookFun["author"]);

const bookObj = {
    checkIn: function() {
        return this;
    }
}

function anotherCheckIn() {
    return this;
}
console.log(bookObj.checkIn() + "\n\n\n");
console.log(bookObj.checkIn() === bookObj);
console.log(anotherCheckIn());
console.log(anotherCheckIn() === globalThis);

function promiseTimeout(ms) {
    return new Promise((resolve, reject) => {
        setTimeout(resolve, ms);
    });
}

promiseTimeout(2000)
    .then(() => {
        console.log('Done!!');
        return promiseTimeout(1000);
    }).then(() => {
        console.log('Also done!!');
    }).catch(() => {
        console.log('Error!!');
    })

function promiseTimeout(ms) {
    return new Promise((resolve, reject) => {
        setTimeout(resolve, ms);
    });
}

async function longRunningOperation() {
    return 43;
}

async function run() {
    console.log("Start!!");
    // promiseTimeout(2000);
    await promiseTimeout(2000);

    // const response = longRunningOperation();
    const response = await longRunningOperation();
    console.log(response);

    console.log("Stop!!");
}

run();

// npm
// npm init
// npm config set registry https://registry.npm.taobao.org
// npm install --save-dev pretter
// npm install express

require("dotenv").config();
const express = require("express");
const app = express();
// const port = 3000;
const port = process.env.PORT;
// 端口号设置在.env文件内
// PORT=5000
// .gitignore文件配置了.env node_modules/

app.get("/", (req, res) => {
    res.send("HelloWorld");
});
app.listen(port, () => {
    console.log(`Example app listening at http://localhost:${port}`);
});
```