sudo apt update

sudo apt install wget -y
wget -qO- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh | bash
export NVM_DIR="$([ -z "${XDG_CONFIG_HOME-}" ] && printf %s "${HOME}/.nvm" || printf %s "${XDG_CONFIG_HOME}/nvm")"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh" # This loads nvm

nvm install 22

node -v

v22.18.0

npm init

This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.

See `npm help init` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.

Press ^C at any time to quit.
package name: (tutorial)
version: (1.0.0)
description:
entry point: (index.js) app.js
test command:
git repository:
keywords:
author: Federico2903
license: (ISC) GPL-3.0-or-later
About to write to D:\Users\asus\Desktop\tutorial\package.json:

{
  "name": "tutorial",
  "version": "1.0.0",
  "description": "",
  "main": "app.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Federico2903",
  "license": "GPL-3.0-or-later"
}


Is this OK? (yes) yes

npm install express --save

12345678const express = require('express');
const app = express();

app.get('/', (req, res) => {
    res.send('Hello World!');
});

app.listen(3000);

node app.js

1234567891011let message = "Hello"; // 用 let 声明变量
const pi = 3.14;       // 用 const 声明常量
if (true) {
    console.log(message);
}
for (let i = 0; i < 5; i++) {
    console.log(i);
}
function greet(name) { // 函数定义
    return "Hello, " + name;
}

123456789101112131415161718#include <iostream>
using namespace std;

string greet(string name) {
    return "Hello, " + name;
}

int main() {
    string message = "Hello";
    const double pi = 3.14;
    if (true) {
        cout << message << endl;
    }
    for (int i = 0; i < 5; i++) {
        cout << i << endl;
    }
    return 0;
}

123console.log("This is the first message.");
throw new Error('Example error'); // 抛出一个错误
console.log("This is the second message.");

This is the first message.
D:\Users\asus\Desktop\tutorial\test.js:2
throw new Error('Example error');
^

Error: Example error
    at Object.<anonymous> (D:\Users\asus\Desktop\tutorial\test.js:2:7)
    at Module._compile (node:internal/modules/cjs/loader:1688:14)
    at Object..js (node:internal/modules/cjs/loader:1820:10)
    at Module.load (node:internal/modules/cjs/loader:1423:32)
    at Function._load (node:internal/modules/cjs/loader:1246:12)
    at TracingChannel.traceSync (node:diagnostics_channel:322:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:235:24)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:171:5)
    at node:internal/main/run_main_module:36:49

Node.js v22.18.0

1234<script src="script.js"></script>
<!-- 这个会加载同目录下的 script.js -->
<script>
    alert('Alert');
</script>
<!-- 这个会在你打开的时候弹出一个提示 -->

{
     "firstName": "John",
     "lastName": "Smith",
     "sex": "male",
     "age": 25,
     "address": {
         "streetAddress": "21 2nd Street",
         "city": "New York",
         "state": "NY",
         "postalCode": "10021"
     },
     "phoneNumber": [
         {
           "type": "home",
           "number": "212 555-1234"
         },
         {
           "type": "fax",
           "number": "646 555-4567"
         }
     ]
 }

12345678910111213141516171819202122232425262728293031323334const json = '{"name":"Federico2903","uid":381949}';
// 这是一个 JSON 字符串
const jsonObject = JSON.parse(json);
// 解析成一个 JSON 对象
console.log(jsonObject.name);
// 输出 Federico2903
console.log(JSON.stringify(jsonObject));
// 输出 {"name":"Federico2903","uid":381949}
// 这就变回了字符串

const coyoteStrengthInfo = {
    type: "msg",
    strength: {
        strengthA: 0,
        strengthALimit: 200,
        strengthB: 0,
        strengthBLimit: 200
    }
};
// 直接定义 JSON 对象也是可以的

console.log(coyoteStrengthInfo.strength.strengthA);
// 输出 0

const coyotePulseInfo = {
    type: "msg",
    pulse: [
        "0A0A0A0A000A141E",
        "0F0F0F0F28323C46"
    ]
}

console.log(coyotePulseInfo.pulse[0]);
// 输出 0A0A0A0A000A141E

1<p style="font-size: 2em; text-align: center;" class="title">An example title</p>

123<style>
p {
    font-size: 2em;
    color: red;
}
</style>
<p>An example paragraph.</p>
<!-- 这段文字会显示为大一些的红色 -->

123{
    Here is you css content.
}

1234567891011span {
    /* 选中所有 <span> */
}

.card {
    /* 选中所有类中含有 card 的元素 */
}

#element {
    /* 选中 ID 是 element 的元素 */
}

123.card-1, .card-2 {
    /* 选中所有类中含有 card-1 或 card-2 的元素 */
}

1app.method(path, handler);

123app.put('/user', (req, res) => {
    res.send('Got a PUT request at /user')
})

12345678910111213141516171819// 正确用法：先设置后发送
app.get('/api/user', (req, res) => {
    res.set('X-Custom-Header', 'value');  // 不结束响应
    res.status(200);                      // 不结束响应
    res.json({ user: 'John' });           // 结束响应
});

// 错误用法：发送后不能再设置
app.get('/error-1', (req, res) => {
    res.send('Hello');                    // 结束响应
    res.set('X-Header', 'value');         // 错误：响应已结束
});

// 错误用法：未结束响应过程
app.get('/error-2', (req, res) => {
    res.set('X-Custom-Header', 'value');  // 不结束响应
    res.status(200);                      // 不结束响应
    // HTTP 连接将一直等待响应结束，但是永远也不会结束，直到超时
});

npm install cookie-parser --save

123456app.use(cookieParser());
// 解析 Cookie
app.use(express.json());
// 解析 application/json
app.use(express.urlencoded({ extended: true }));
// 解析 application/x-www-form-urlencoded

123app.post('/', (req, res) => {
    res.send(req.body);
});

sudo apt install curl -y

curl -X POST -H "Content-Type: application/json" -d "{\"x\":1}" http://localhost:3000
        ^            ^                                    ^             ^
  指定请求方法    指定是 JSON 格式                      请求体           网址

$ curl -X POST -H "Content-Type: application/json" -d "{\"x\":1}" http://localhost:3000
{"x":1}

$ node app.js
{ x: 1 }

123app.post('/', (req, res) => {
    res.send(`Hello, ${req.body.username}`);
});

$ curl -X POST -H "Content-Type: application/json" -d "{\"username\":\"Federico2903\"}" http://localhost:3000
Hello, Federico2903

1app.get('/user/:id', (req, res) => res.send(req.params.id));

1234app.get('/search', (req, res) => {
    console.log(req.query);
    res.send(`搜索关键词：${req.query.keyword}，限制条数：${req.query.limit}`);
});

{ keyword: 'node', limit: '10' }

搜索关键词：node，限制条数：10