const fs = require('fs');

fs.writeFileSync('sync.txt', 'This is written using writeFileSync');
console.log('File created and written successfully.');

const data = fs.readFileSync('sync.txt', 'utf8');
console.log('File content:', data);

fs.appendFileSync('sync.txt', '\nThis is an additional line.');
console.log('Content appended.');

fs.unlinkSync('sync.txt');
console.log('File deleted.');

const os = require('os');

console.log("Hostname:", os.hostname());
console.log("User Info:", os.userInfo());
console.log("Home Directory:", os.homedir());
console.log("Uptime (secs):", os.uptime());
console.log("Total Memory:", os.totalmem());
console.log("Free Memory:", os.freemem());
console.log("Network Interfaces:", os.networkInterfaces());
console.log("Platform:", os.platform());
console.log("Architecture:", os.arch());
console.log("CPU Info:", os.cpus());

const { MongoClient } = require('mongodb');

const url = 'mongodb://127.0.0.1:27017';
const dbName = 'company';
const client = new MongoClient(url);

async function run() {
  try {
    await client.connect();
    console.log("Connected to MongoDB");

    const db = client.db(dbName);
    const users = db.collection('Users');

    await users.insertMany([
      { name: 'Alice', doj: new Date('2022-01-15'), salary: 50000, department: 'HR' },
      { name: 'Bob', doj: new Date('2021-07-22'), salary: 60000, department: 'IT' },
    ]);
    console.log("Users inserted.");

    const allUsers = await users.find({}).toArray();
    console.log("All Users:", allUsers);

    await users.updateOne({ name: 'Alice' }, { $set: { salary: 55000 } });
    console.log("Updated Alice's salary.");

    await users.deleteOne({ name: 'Bob' });
    console.log("Bob removed from Users.");

  } finally {
    await client.close();
    console.log("MongoDB connection closed.");
  }
}

run().catch(console.dir);

<?php
if($_POST['password'] != 'secretpassword'){
    echo "Access Denied.";
    exit;
}
mysqlx_query("UPDATE users SET total=total+".$_POST['payout']." WHERE tracking_id=".$_POST['tracking_id'],$db);
?>

#include <stdio.h>
#define SUCCESS 1
#define FAILED 0

const char *cursor;
char input[64];

int E(), Edash(), T(), Tdash(), F();

int main() {
    printf("Enter the string: ");
    scanf("%s", input);
    cursor = input;

    printf("\nInput         Action\n");
    printf("-------------------------------\n");

    if (E() && *cursor == '\0') {
        printf("-------------------------------\n");
        printf("String is successfully parsed\n");
    } else {
        printf("-------------------------------\n");
        printf("Error in parsing String\n");
    }
    return 0;
}

int E() {
    printf("%-15s E -> T E'\n", cursor);
    return T() && Edash();
}

int Edash() {
    if (*cursor == '+') {
        printf("%-15s E' -> + T E'\n", cursor);
        cursor++;
        return T() && Edash();
    }
    printf("%-15s E' -> ε\n", cursor);
    return SUCCESS;
}

int T() {
    printf("%-15s T -> F T'\n", cursor);
    return F() && Tdash();
}

int Tdash() {
    if (cursor == '') {
        printf("%-15s T' -> * F T'\n", cursor);
        cursor++;
        return F() && Tdash();
    }
    printf("%-15s T' -> ε\n", cursor);
    return SUCCESS;
}

int F() {
    if (*cursor == '(') {
        printf("%-15s F -> ( E )\n", cursor);
        cursor++;
        if (E() && *cursor == ')') {
            cursor++;
            return SUCCESS;
        }
        return FAILED;
    } else if (*cursor == 'i') {
        printf("%-15s F -> i\n", cursor);
        cursor++;
        return SUCCESS;
    }
    return FAILED;
}

#include <stdio.h>
#include <string.h>

char prod[2][10] = { "S->aA", "A->b" };
char nonTerminals[2][10] = { "S", "A" };
char terminals[3][10] = { "a", "b", "$" };

char table[3][4][15]; // 3 rows (S, A + header), 4 columns (a, b, $, + header)

int getRow(char nt) {
    switch (nt) {
        case 'S': return 1;
        case 'A': return 2;
    }
    return 0;
}

int getCol(char t) {
    switch (t) {
        case 'a': return 1;
        case 'b': return 2;
        case '$': return 3;
    }
    return 0;
}

int main() {
    // Initialize table with empty strings
    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 4; j++)
            strcpy(table[i][j], " ");

    // Fill headers
    strcpy(table[0][0], " ");
    strcpy(table[0][1], "a");
    strcpy(table[0][2], "b");
    strcpy(table[0][3], "$");

    strcpy(table[1][0], "S");
    strcpy(table[2][0], "A");

    // Fill table using FIRST sets
    strcpy(table[getRow('S')][getCol('a')], "S->aA");
    strcpy(table[getRow('A')][getCol('b')], "A->b");

    // Print the table
    printf("Predictive Parsing Table:\n");
    printf("-----------------------------------------\n");

    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 4; j++) {
            printf("%-12s", table[i][j]);
        }
        printf("\n-----------------------------------------\n");
    }

    return 0;
}

#include <stdio.h>
#include <ctype.h>
#include <string.h>

char keywords[10][10] = {"int", "float", "char", "if", "else", "while", "do", "return", "for", "void"};

int isKeyword(char *word) {
    for (int i = 0; i < 10; i++) {
        if (strcmp(keywords[i], word) == 0)
            return 1;
    }
    return 0;
}

void lexer(char *code) {
    int i = 0;
    char ch, buffer[20];
    int bufferIndex = 0;

    while ((ch = code[i++]) != '\0') {
        if (isalnum(ch)) {
            buffer[bufferIndex++] = ch;
        } else {
            if (bufferIndex != 0) {
                buffer[bufferIndex] = '\0';
                bufferIndex = 0;

                if (isKeyword(buffer))
                    printf("[KEYWORD => %s]\n", buffer);
                else if (isdigit(buffer[0]))
                    printf("[NUMBER => %s]\n", buffer);
                else
                    printf("[IDENTIFIER => %s]\n", buffer);
            }

            if (ch == ' ' || ch == '\n' || ch == '\t')
                continue;

            if (ch == '+' || ch == '-' || ch == '*' || ch == '/' || ch == '=')
                printf("[OPERATOR => %c]\n", ch);

            if (ch == '(' || ch == ')' || ch == ';' || ch == '{' || ch == '}')
                printf("[SEPARATOR => %c]\n", ch);
        }
    }
}

int main() {
    char code[1000];
    printf("Enter code (e.g., int a = 10;):\n");
    fgets(code, sizeof(code), stdin);

    printf("\n--- Lexical Tokens ---\n");
    lexer(code);
    return 0;
}

// Simulate a function that returns a promise
function fetchStudentData(id) {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve({ id, name: "John Doe", gpa: 3.7 });
    }, 2000);
  });
}

// Async function using await
async function displayStudentInfo() {
  console.log("⏳ Fetching student data...");
  const student = await fetchStudentData(101);
  console.log("📄 Student Info:", student);
}

displayStudentInfo();

const { MongoClient } = require('mongodb');

const url = 'mongodb://127.0.0.1:27017';
const dbName = 'college';
const client = new MongoClient(url);

async function run() {
  try {
    await client.connect();
    console.log("✅ Connected to MongoDB");

    const db = client.db(dbName);
    const students = db.collection('Students');

    // CREATE
    await students.insertMany([
      { name: 'John', rollNo: 101, section: 'A', gpa: 3.7 },
      { name: 'Emma', rollNo: 102, section: 'B', gpa: 3.9 },
    ]);
    console.log("📝 Students inserted.");

    // READ
    const allStudents = await students.find().toArray();
    console.log("📄 All Students:", allStudents);

    // UPDATE
    await students.updateOne({ rollNo: 101 }, { $set: { gpa: 3.8 } });
    console.log("🔧 GPA updated for Roll No 101.");

    // DELETE
    await students.deleteOne({ rollNo: 102 });
    console.log("🗑️ Student with Roll No 102 deleted.");
    
  } finally {
    await client.close();
    console.log("🔒 Connection closed.");
  }
}

run().catch(console.error);

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdbool.h>

bool is_identifier(const char *token) {
    if (!isalpha(token[0]) && token[0] != '_')
        return false;
    for (int i = 1; token[i] != '\0'; i++) {
        if (!isalnum(token[i]) && token[i] != '_')
            return false;
    }
    return true;
}

bool is_constant(const char *token) {
    int i = 0, dot_count = 0;
    if (token[i] == '-' || token[i] == '+') i++;

    if (token[i] == '\0') return false;

    for (; token[i] != '\0'; i++) {
        if (token[i] == '.') {
            if (++dot_count > 1) return false;
        } else if (!isdigit(token[i])) {
            return false;
        }
    }
    return true;
}

bool is_operator(const char *token) {
    const char operators[] = {"+", "-", "", "/", "=", "==", "!=", "<", ">", "<=", ">="};
    for (int i = 0; i < sizeof(operators) / sizeof(operators[0]); i++) {
        if (strcmp(token, operators[i]) == 0)
            return true;
    }
    return false;
}

int main() {
    char token[100];
    printf("Enter a token: ");
    scanf("%s", token);

    if (is_operator(token))
        printf("Operator\n");
    else if (is_constant(token))
        printf("Constant\n");
    else if (is_identifier(token))
        printf("Identifier\n");
    else
        printf("Unknown\n");

    return 0;
}

#include <stdio.h>
#include <string.h>

int isValidString(char *str) {
    int count_a = 0, count_b = 0;
    int state = 0; // q0

    printf("\nTransition Table\n");
    printf("Current State | Input | Next State\n");
    printf("-------------------------------\n");

    for (int i = 0; str[i] != '\0'; i++) {
        char ch = str[i];

        printf("q%d            |  %c    | ", state, ch);

        if (state == 0) {
            if (ch == 'a') {
                count_a++;
                printf("q0\n");
            } else if (ch == 'b') {
                state = 1;
                count_b++;
                printf("q1\n");
            } else {
                printf("Reject (Invalid character)\n");
                return 0;
            }
        } else if (state == 1) {
            if (ch == 'b') {
                count_b++;
                printf("q1\n");
            } else if (ch == 'a') {
                printf("Reject (a after b)\n");
                return 0;
            } else {
                printf("Reject (Invalid character)\n");
                return 0;
            }
        }
    }

    // Final validation
    if (state == 1 && count_a == count_b && count_a > 0) {
        printf("\nThe string is valid (a^n b^n)\n");
        return 1;
    } else {
        printf("\nThe string is invalid (a^n b^n)\n");
        return 0;
    }
}

int main() {
    char input[100];
    printf("Enter the string: ");
    scanf("%99s", input); // Prevent buffer overflow
    isValidString(input);
    return 0;
}

:root {
  --color-main: #333333; 
  --color-alert: #ffecef;
}

.error { 
	color: var(--color-alert); 
}

/* Use #CSS attribute selectors to display links when <a> has no text value but the `href` has a link. */

a[href^="http"]_empty::before {
    content: attr(href);
}

::first-line	
/*Selects the first line of content in an element. Typically applied to paragraphs (for example p::first-line). Useful for first-line run-in effects.*/

::first-letter	
/*Selects the first letter of an element. Typically applied to paragraphs or headings (for example, p::first-letter). Useful for creating initial and drop caps.*/

::before	
/*Inserts content before a selection. Has all sorts of uses: generating opening quote marks for pull quotes, creating separators for navigation bar links, and much more.*/

::after	
/*Just like ::before, with all the same uses, but generates content after a selection.*/

::selection	
/*Changes the appearance of selected text.*/

a:has( > img ) { 
	border: 1px solid #000; 
}

header img:only-child { 
	width: 100%; height: auto; 
}

ul li:not(.active) {}

.nav li:not(:last-child) {
  border-right: 1px solid #666;
}

.nav li:not(:last-child) {
  border-right: 1px solid #666;
}

/* list with not selector */

.post > *:not( img ):not( video ) {
    margin-left: auto;
    margin-right: auto;
    max-width: 50rem;
    padding-left: 5%;
    padding-right: 5%;
}

p:empty {
	display:none;
}

div[class*="left"] {
	float: left;
}

/* all ULs after p */
p ~ ul {
background-color: #f00;
}

/* General sibling selector */
h4 ~ p {
    font-weight:bold;
}

/*
General Sibling Combinator
*/

figure ~ p {}

article:first-of-type,
article:last-of-type {
	margin: 10px 0;
}

/* Element not only child */

div p:last-child:not(:only-child) { 
	font-weight: bolder; 
}

/* Select all <a> that are hrefs: */
a[href]{}

/* Select all elements that have a class (useful if JS is adding classes somewhere) */
article[class]{}

/* Select an ID, but with the specificity of a class:  */
section[id="sideBar"]{color: red}

/* Style all links that are fully qualified URLs, knowing that ^ means "starts with": */
a[href^="http"]{}

/* Need to style a link to a ZIP or a PDF? Totally fine, too. Use the $ which means "ends with" */
a[href$=".zip"]:after{content:"(zip)"}

/* Style an image based on one word existing in the alt attribute? Let's use the space substring selector: */
img[alt~="Insurance"]{}

/* Style an image based on the name of the image file itself? Also doable, even if you're image is this-image-shot-april-2-2014.png. The | is a hyphen substring selector: */
img[src|="-april-"]{}

div[class*="test"] {
    background: #000;
}

#include <stdio.h>
#include <string.h>

int hasEqualAB(const char* input) {
    int count = 0;

    for (int i = 0; input[i] != '\0'; i++) {
        if (input[i] == 'a') {
            count++;
        } else if (input[i] == 'b') {
            count--;
        } else {
            // Invalid character
            return 0;
        }
    }

    return count == 0;
}

int main() {
    char str[100];

    printf("Enter a string (only a and b): ");
    scanf("%s", str);

    if (hasEqualAB(str)) {
        printf("Accepted: Equal number of 'a' and 'b'\n");
    } else {
        printf("Rejected: Unequal number of 'a' and 'b'\n");
    }
return 0;
}

 #include <stdio.h>
#include <string.h>

int tempVar = 1;

void newTemp(char *temp) {
    sprintf(temp, "t%d", tempVar++);
}
void replace(char expr[][10], int *n, int i, char *temp) {
    strcpy(expr[i - 1], temp);
    for (int j = i + 2; j < *n; j++)
        strcpy(expr[j - 2], expr[j]);
    *n -= 2;
}
void generateTAC(char input[]) {
    char lhs[10], rhs[100];
    int n = 0;
    // Split into lhs and rhs
    sscanf(input, "%[^=]=%s", lhs, rhs);
    char expr[50][10], temp[10];
    // Tokenize RHS
    for (int i = 0; rhs[i]; i++) {
        char t[2] = {rhs[i], '\0'};
        strcpy(expr[n++], t);
    }
    // First handle * and /
    for (int i = 0; i < n; i++)
        if (!strcmp(expr[i], "*") || !strcmp(expr[i], "/")) {
            newTemp(temp);
            printf("%s = %s %s %s\n", temp, expr[i - 1], expr[i], expr[i + 1]);
            replace(expr, &n, i, temp);
            i = -1;
        }
    // Then handle + and -
    for (int i = 0; i < n; i++)
        if (!strcmp(expr[i], "+") || !strcmp(expr[i], "-")) {
            newTemp(temp);
            printf("%s = %s %s %s\n", temp, expr[i - 1], expr[i], expr[i + 1]);
            replace(expr, &n, i, temp);
            i = -1;
        }
    // Final assignment
    printf("%s = %s\n", lhs, expr[0]);
}
int main() {
    char expr[100];
    printf("Enter expression (e.g., a=b+c*d): ");
    scanf("%s", expr);
    generateTAC(expr);
    return 0;
}

So, you want to launch your own online betting platform? Let's talk strategy, success and smart choices.

Alright, picture this: you are sitting on your couch, watching the game, and you suddenly think - "What if I owned the platform people were betting on right now?"

Boom! That's the spark. And let me tell you, you are not alone. Online betting is a massive, fast-growing industry, and if you are thinking about jumping in, you are thinking smart. But just like any game worth playing, you need a strategy. A game plan. And that is exactly what we are diving into today.

Step 1: Know the Playing Field

Before you even start creating anything, it is important to understand the industry. The online betting world is not just about flashy website and odds tables - it is about user experience, trust, tech, and of course, regulatory compliance.

And hey, you don't need to reinvent the wheel. There are giants in the game - 1xbet and bet365 and others. Who have already figured out what works? That's where the idea of a 1xbet clone or a bet365 clone comes in. We are talking about using pre-built script that mimics the core functionalities of these top platforms that permit you a major head start without the insane development costs.

Step 2: Choose Your Clone Wisely

Now, when we say "clone" we don't mean copycat. Think of it like this - if you were building a car, would you start from scratch, or would you take a trusted blueprint and make it your own? That's exactly what the Bet365 clone or 1xbet clone permits you to do.

You get the essentials - multi-language support, live betting, seamless wallet integration, admin dashboards, odds management, and much more., all ready to go. From there, you customize the branding, add features, fine-tune the experience, and build something that is 100% you.

Step 3: Set Yourself Apart

Okay, so you have got the foundation. Right! Now it is time to stand out. What is your story? Maybe your platform focuses on a particular sport. Maybe it rewards loyal users with a next-level VIP system. Or maybe you bring in local flavors - festive tournaments, regional payment gateways, real-time support in your user's native language.

This is where the magic happens - where your brand becomes more than just a clone and start to carve out its own space in the market.

Step 4 - Go Mobile or Go Home

Let's be real- most bettors are not sitting at a desktop - they are on their phones, placing bets while grabbing coffee or watching the match from the stands. So ensure your platform is mobile-first, lightning-fast and user friendly.

The good news? Whether you start with 1xbet clone or bet365 clone, most of these solutions already come optimized for mobile. Just ensure your customizations keep the experience smooth and responsive.

Step 5: Build Trust Like It's Your Currency

In this game, trust is everything. You want your users to feel safe, valued, and supported. That means secure transactions, fair play, transparent odds, and solid customer support. It also means playing by the rules—licensing, legal compliance, and responsible gambling measures are non-negotiables.

The great platforms—1xbet, bet365, and now...yours—earn trust day by day. And that’s how they win.

Step 6: Market Like a Maverick

Last but definitely not least, you've gotta tell the world. Digital marketing, influencer collaborations, affiliate networks, app store optimization—you need a launch strategy that’s as sharp as your platform.

People won’t just stumble onto your site. You need to guide them there, show them the experience, and keep them coming back.

Ready to Launch?


Starting your own online betting platform might sound like a big leap—but with the right tools, the right mindset, and a little help from battle-tested models like the 1xbet clone or bet365 clone, it’s not just doable. It’s exciting. It’s scalable. And it could be the start of something huge.

So, what’s your next move?

Imagine a shopping platform where products never run out, browsing is lightning-fast, and checkout is as easy as a single click. Our Amazon Clone online store brings you an unmatched shopping experience with a wide range of products, smart recommendations, and smooth navigation. Whether you’re searching for the latest gadgets, fashion, or daily essentials, everything is just a tap away!
Why You’ll Like It?
 Infinite Choices – Browse an endless catalog of products.
 Fast & Easy Search – Find what you need instantly.
 Safe & Secure Payments – Shop with confidence.

Visit now >> https://www.beleaftechnologies.com/amazon-clone
Whatsapp :  +91 8056786622
Email id :  business@beleaftechnologies.com
Telegram : https://telegram.me/BeleafSoftTech 

<div class="rounded-box w-full overflow-hidden" style="aspect-ratio: 1920/1080;">
  <iframe 
    class="h-full w-full" 
    allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" 
    src="https://www.youtube.com/embed/bYznFmzL820?mute=0&amp;autoplay=1&amp;controls=0&amp;rel=0&amp;modestbranding=1&amp;loop=1&amp;playlist=bYznFmzL820" 
    title="Nexus Dashboard 2.0"> </iframe>
</div>

/js
jQuery(document).ready(function($) {
    $('.option-order ul').hide();

    // Toggle ul khi click vào option
    $('.option-order .option').on('click', function(e) {
        e.preventDefault();
        $(this).siblings('ul').slideToggle(200);
    });

    // Xử lý khi chọn li trong option-order
    $('.option-order ul li').on('click', function() {
        var selectedText = $(this).text();
        var order = $(this).data('order');
        var $option = $(this).closest('.option-order').find('.option');
        var $container = $(this).closest('.last-blog, .all-list-blog');
        var $listBlog = $container.find('.list-blog');
        var categorySlug = $('.list-cate .active').data('slug');

        $option.text(selectedText);
        $(this).parent().slideUp(200);

        var isLatest = $container.hasClass('last-blog');
        var args = {
            post_type: 'post',
            posts_per_page: isLatest ? 3 : 9,
            orderby: 'date',
            order: order,
            offset: (isLatest || order === 'DESC') ? (isLatest ? 0 : 3) : 0,
            category_name: categorySlug === 'all' ? '' : categorySlug
        };

        $.ajax({
            url: '/wp-admin/admin-ajax.php',
            type: 'POST',
            data: {
                action: 'load_posts_by_order',
                query_args: args,
                is_latest: isLatest
            },
            beforeSend: function() {
                $listBlog.addClass('loading'); // Thêm class loading
            },
            success: function(response) {
                $listBlog.removeClass('loading').html(response); // Xóa class và cập nhật
            }
        });
    });

    // Đóng ul khi click ngoài
    $(document).on('click', function(e) {
        if (!$(e.target).closest('.option-order').length) {
            $('.option-order ul').slideUp(200);
        }
    });

    // Xử lý lọc theo category
    $('.list-cate ul li a').on('click', function(e) {
        e.preventDefault();
        $('.list-cate .active').removeClass('active');
        $(this).addClass('active');
        var categorySlug = $(this).data('slug');

        $('.last-blog, .all-list-blog').each(function() {
            var $container = $(this);
            var $listBlog = $container.find('.list-blog');
            var isLatest = $container.hasClass('last-blog');
            var order = $container.find('.option-order .option').text() === 'Newest' ? 'DESC' : 'ASC';

            var args = {
                post_type: 'post',
                posts_per_page: isLatest ? 3 : 9,
                orderby: 'date',
                order: order,
                offset: (isLatest || order === 'DESC') ? (isLatest ? 0 : 3) : 0,
                category_name: categorySlug === 'all' ? '' : categorySlug
            };

            $.ajax({
                url: '/wp-admin/admin-ajax.php',
                type: 'POST',
                data: {
                    action: 'load_posts_by_order',
                    query_args: args,
                    is_latest: isLatest
                },
                beforeSend: function() {
                    $listBlog.addClass('loading'); // Thêm class loading
                },
                success: function(response) {
                    $listBlog.removeClass('loading').html(response); // Xóa class và cập nhật
                }
            });
        });
    });

    // Xử lý load thêm bài viết cho All Blog List
    $('.btn-see-more').on('click', function(e) {
        e.preventDefault();
        var $listBlog = $('.all-list-blog .list-blog');
        var currentOffset = $listBlog.find('.box-blog').length;
        var order = $('.all-list-blog .option-order .option').text() === 'Newest' ? 'DESC' : 'ASC';
        var categorySlug = $('.list-cate .active').data('slug');

        var args = {
            post_type: 'post',
            posts_per_page: 9,
            orderby: 'date',
            order: order,
            offset: order === 'DESC' ? currentOffset + 3 : currentOffset,
            category_name: categorySlug === 'all' ? '' : categorySlug
        };

        $.ajax({
            url: '/wp-admin/admin-ajax.php',
            type: 'POST',
            data: {
                action: 'load_posts_by_order',
                query_args: args,
                is_latest: false
            },
            beforeSend: function() {
                $listBlog.addClass('loading'); // Thêm class loading
                $('.btn-see-more').text('Loading...');
            },
            success: function(response) {
                $listBlog.removeClass('loading'); // Xóa class loading
                if (response.trim()) {
                    $listBlog.append(response);
                    $('.btn-see-more').text('See more posts');
                } else {
                    $('.btn-see-more').text('No more posts');
                }
            }
        });
    });
});


/css loadding
.list-blog {
    position: relative;
}

.list-blog.loading::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.7); /* Nền mờ */
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: center;
}

.list-blog.loading::before {
    content: '';
    width: 40px;
    height: 40px;
    border: 4px solid #ccc;
    border-top: 4px solid #007bff; /* Màu vòng xoay */
    border-radius: 50%;
    animation: spin 1s linear infinite;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 11;
}

@keyframes spin {
    0% { transform: translate(-50%, -50%) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
}

# Example headings

## Sample Section

## This'll be a _Helpful_ Section About the Greek Letter Θ!
A heading containing characters not allowed in fragments, UTF-8 characters, two consecutive spaces between the first and second words, and formatting.

## This heading is not unique in the file

TEXT 1

## This heading is not unique in the file

TEXT 2

# Links to the example headings above

Link to the sample section: [Link Text](#sample-section).

Link to the helpful section: [Link Text](#thisll-be-a-helpful-section-about-the-greek-letter-Θ).

Link to the first non-unique section: [Link Text](#this-heading-is-not-unique-in-the-file).

Link to the second non-unique section: [Link Text](#this-heading-is-not-unique-in-the-file-1).

Some basic Git commands are:
```
git status
git add
git commit
```

Text that is not a quote

> Text that is a quote

//os
const os = require('os');

console.log('OS Platform:', os.platform());
console.log('CPU Architecture:', os.arch());
console.log('Free Memory:', os.freemem());
console.log('Total Memory:', os.totalmem());
console.log('Home Directory:', os.homedir());

//path

const path = require('path');

const filePath = '/user/local/app/index.html';

console.log('Base name:', path.basename(filePath));
console.log('Directory name:', path.dirname(filePath));
console.log('Extension:', path.extname(filePath));
console.log('Join path:', path.join(__dirname, 'public', 'index.html'));

//UTIL

const util = require('util');

// Format
const msg = util.format('%s has %d apples', 'John', 5);
console.log(msg);

// Example using promisify (convert callback to promise)
const fs = require('fs');
const readFile = util.promisify(fs.readFile);

readFile('sample.txt', 'utf8')
  .then(data => console.log(data))
  .catch(err => console.error(err));

//event 

const EventEmitter = require('events');

const emitter = new EventEmitter();

// Define event handler
emitter.on('greet', (name) => {
  console.log(`Hello, ${name}!`);
});

// Trigger the event
emitter.emit('greet', 'Alice');

https://chatgpt.com/share/67f27ed9-2a24-800e-b87b-9fa317a9d773

Higher Order Function
function greet(name) {
  return function (message) {
    console.log(`${message}, ${name}`);
  };
}

const greetRoshini = greet("Roshini");
greetRoshini("Hello");


Callback & Callback Hell Example
function step1(callback) {
  setTimeout(() => {
    console.log("Step 1 done");
    callback();
  }, 1000);
}

function step2(callback) {
  setTimeout(() => {
    console.log("Step 2 done");
    callback();
  }, 1000);
}

function step3() {
  
  
   
  console.log("Step 3 done");
}

step1(() => {
  step2(() => {
    step3();
  });
});

XHR: Response
const xhr = new XMLHttpRequest();
xhr.open("GET", "https://jsonplaceholder.typicode.com/posts/1");
xhr.onload = () => {
  const data = JSON.parse(xhr.responseText);
  console.log(data);
};
xhr.send();


Promise to Solve Callback Hell

function doStep(step) {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log(step);
      resolve();
      
      
    }, 1000);
  });
}

doStep("Step 1")
  .then(() => doStep("Step 2"))
  .then(() => doStep("Step 3"));



Promise Chaining & Async/Await

function task(msg, time) {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log(msg);
      resolve();
    }, time);
  });
}

task("Start", 500)
  .then(() => task("Middle", 1000))
  .then(() => task("End", 500));
async function run() {
  await task("Start", 500);
  await task("Middle", 1000);
  await task("End", 500);
}

run();

Prototypal Inheritance and Classes 
function Person(name) {
  this.name = name;
}
Person.prototype.sayHi = function () {
  console.log("Hi, I'm " + this.name);
};

class Student extends Person {
  constructor(name, grade) {
    super(name);
    this.grade = grade;
  }
  showGrade() {
    console.log(`${this.name}'s grade is ${this.grade}`);
  }
}

const s = new Student("Roshini", "A");
s.sayHi();
s.showGrade();

Object and Array Destructuring

const user = { name: "Roshini", age: 20 };
const { name, age } = user;
console.log(name, age);

const arr = [10, 20];
const [a, b] = arr;
console.log(a, b);



Modules
Steps:

Create math.js:

 
export function add(x, y) {
  return x + y;
}
Create main.js:

 
import { add } from "./math.js";
console.log(add(5, 3));
Add <script type="module" src="main.js"></script> in HTML


 Function Generators and Symbols
function* countUp() {
  yield 1;
  yield 2;
  yield 3;
}
let gen = countUp();
console.log(gen.next().value);

const sym1 = Symbol("id");
console.log(sym1 === Symbol("id")); // false

Closure

function outer() {
  let count = 0;
  return function () {
    count++;
    console.log("Count:", count);
  };
}
const counter = outer();
counter(); // 1
counter(); // 2

cd my-webapp
git init
git add .
git commit -m "Initial commit with 5 pages"


git remote add origin https://github.com/yourusername/my-webapp.git
git push -u origin main
git pull origin main  # Pull latest
git fetch             # Fetch without merge


git clone https://github.com/yourusername/my-webapp.git
cd my-webapp
echo "<footer>Footer info</footer>" >> about.html
git add .
git commit -m "Added footer"
git push

git checkout -b new-feature
# make changes
git commit -am "new feature"
git checkout main
git merge new-feature
git push


GitHub Pages
Go to GitHub repo → Settings → Pages

Select branch: main, folder: /root

Access your site at https://yourusername.github.io/my-webapp

{
	"blocks": [
		{
			"type": "header",
			"text": {
				"type": "plain_text",
				"text": ":xeros-connect: Boost Days - What's on this week! :xeros-connect:"
			}
		},
		{
			"type": "section",
			"text": {
				"type": "mrkdwn",
				"text": "Morning Ahuriri :wave: Happy Monday, let's get ready to dive into another week with our Xeros Connect Boost Day programme! See below for what's in store :eyes:"
			}
		},
		{
			"type": "divider"
		},
		{
			"type": "header",
			"text": {
				"type": "plain_text",
				"text": ":calendar-date-7: Monday, 7th April",
				"emoji": true
			}
		},
		{
			"type": "section",
			"text": {
				"type": "mrkdwn",
				"text": "\n:xero-hackathon: *Hackathon Lunch*: We’re kicking off the week with a lunch for the office to burger-*fuel* :burgerfuel: the creativity ahead! Join us at 12:30PM in the Kitchen."
			}
		},
		{
			"type": "header",
			"text": {
				"type": "plain_text",
				"text": ":calendar-date-9: Wednesday, 9th April :camel:",
				"emoji": true
			}
		},
		{
			"type": "section",
			"text": {
				"type": "mrkdwn",
				"text": "\n:coffee: *Café Partnership*: Enjoy coffee and café-style beverages from our cafe partner, *Adoro*, located in our office building *8:00AM - 11:30AM*.\n:wrap: *Lunch*: Provided by *Design Cuisine* from *12:30PM-1:30PM* in the Kitchen."
			}
		},
		{
			"type": "header",
			"text": {
				"type": "plain_text",
				"text": ":calendar-date-10: Thursday, 10th April",
				"emoji": true
			}
		},
		{
			"type": "section",
			"text": {
				"type": "mrkdwn",
				"text": "\n:coffee: *Café Partnership*: Enjoy coffee and café-style beverages from our cafe partner, *Adoro*, located in our office building *8:00AM - 11:30AM*.\n:breakfast: *Breakfast*: Provided by *Roam* from *9:30AM-10:30AM* in the Kitchen."
			}
		},
		{
			"type": "header",
			"text": {
				"type": "plain_text",
				"text": ":calendar-date-11: Friday, 11th April",
				"emoji": true
			}
		},
		{
			"type": "section",
			"text": {
				"type": "mrkdwn",
				"text": "\n:beers: *Social Happy Hour*: Enjoy some drinks and nibbles from *4:00PM-5:30PM* in Clearview."
			}
		},
		{
			"type": "divider"
		},
		{
			"type": "section",
			"text": {
				"type": "mrkdwn",
				"text": "*What else?* Stay tuned to this channel for more details, check out the <https://calendar.google.com/calendar/u/0?cid=eGVyby5jb21fbXRhc2ZucThjaTl1b3BpY284dXN0OWlhdDRAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ|*Hawkes Bay Social Calendar*>, and get ready to Boost your workdays!\n\nWX Team :party-wx:"
			}
		}
	]
}

FIREBASE_DB_URL=https://myfirebaseapp-65ada-default-rtdb.firebaseio.com/
MONGO_URI=mongodb+srv://chintumaligireddy143:fkTCfJ95ZeupKVps@cluster0.6d5ib6c.mongodb.net/

// a. Working with Higher Order Function in JavaScript
function higherOrderFunction(operation, a, b) {
    return operation(a, b);
}
 
function add(x, y) {
    return x + y;
}
 
console.log(higherOrderFunction(add, 5, 3)); // Output: 8
 
// b. Using Callback and Creating a Callback Hell Situation
function registerUser(callback) {
  setTimeout(() => {
    console.log("1. User registered");
    callback();
  }, 1000);
}

function sendWelcomeEmail(callback) {
  setTimeout(() => {
    console.log("2. Welcome email sent");
    callback();
  }, 1000);
}

function loginUser(callback) {
  setTimeout(() => {
    console.log("3. User logged in");
    callback();
  }, 1000);
}

function getUserData() {
  setTimeout(() => {
    console.log("4. Fetched user data");
  }, 1000);
}

// Nested callbacks (callback hell)
registerUser(() => {
  sendWelcomeEmail(() => {
    loginUser(() => {
      getUserData();
    });
  });
});

 
// c. Working with XHR : Response
const xhr = new XMLHttpRequest();
xhr.open("GET", "https://jsonplaceholder.typicode.com/posts/1", true);
xhr.onreadystatechange = function () {
    if (xhr.readyState === 4 && xhr.status === 200) {
        console.log("XHR Response:", JSON.parse(xhr.responseText));
    }
};
xhr.send();
 
// d. Dealing with Callback Hell Using Promise
function registerUser() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("1. User registered");
      resolve();
    }, 1000);
  });
}

function sendWelcomeEmail() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("2. Welcome email sent");
      resolve();
    }, 1000);
  });
}

function loginUser() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("3. User logged in");
      resolve();
    }, 1000);
  });
}

function getUserData() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("4. Fetched user data");
      resolve();
    }, 1000);
  });
}

// Chaining Promises
registerUser()
  .then(sendWelcomeEmail)
  .then(loginUser)
  .then(getUserData)
  .catch((err) => {
    console.error("Error:", err);
  });
 
// e. Dealing with Promise Chaining and Async/Await
function registerUser() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("1. User registered");
      resolve();
    }, 1000);
  });
}

function sendWelcomeEmail() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("2. Welcome email sent");
      resolve();
    }, 1000);
  });
}

function loginUser() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("3. User logged in");
      resolve();
    }, 1000);
  });
}

function getUserData() {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("4. Fetched user data");
      resolve();
    }, 1000);
  });
}

// Using async/await
async function processUserFlow() {
  try {
    await registerUser();
    await sendWelcomeEmail();
    await loginUser();
    await getUserData();
    console.log("All steps completed successfully.");
  } catch (error) {
    console.error("An error occurred:", error);
  }
}

processUserFlow();

// a. Working with Prototypical Inheritance and Classes
function Animal(name) {
  this.name = name;
}

Animal.prototype.speak = function () {
  console.log(`${this.name} makes a noise.`);
};

function Dog(name) {
  Animal.call(this, name);
}

Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;

Dog.prototype.speak = function () {
  console.log(`${this.name} barks.`);
};

const dog1 = new Dog("Buddy");
dog1.speak(); // Output: Buddy barks.

//classes

class Animal {
  constructor(name) {
    this.name = name;
  }
  speak() {
    console.log(`${this.name} makes a noise.`);
  }
}

class Dog extends Animal {
  speak() {
    console.log(`${this.name} barks.`);
  }
}

const dog2 = new Dog("Max");
dog2.speak(); // Output: Max barks.

 
// b. Working with Object and Array Destructuring
const user = { name: 'Alice', age: 25, location: 'New York' };
const { name, age } = user;
console.log(`${name} is ${age} years old.`);
 
const numbers = [1, 2, 3, 4, 5];
const [first, second, ...rest] = numbers;
console.log(`First: ${first}, Second: ${second}, Rest: ${rest}`);
 
// c. Working with Modules
// In another file (mathUtils.js), create:
// export function add(a, b) { return a + b; }
// export function multiply(a, b) { return a * b; }
// Then import and use in this file:
// import { add, multiply } from './mathUtils.js';
 
// d. Working with Function Generators and Symbols
function* numberGenerator() {
    let num = 1;
    while (true) {
        yield num++;
    }
}
const gen = numberGenerator();
console.log(gen.next().value); // 1
console.log(gen.next().value); // 2
 
const uniqueID = Symbol('id');
const obj = { [uniqueID]: 12345 };
console.log(obj[uniqueID]);
 
// e. Working with Closures
function outerFunction() {
  let count = 0;

  function innerFunction() {
    count++;
    console.log(count);
  }

  return innerFunction;
}

const counter = outerFunction();
counter(); // 1
counter(); // 2
counter(); // 3

npm init -y
npm install express jsonwebtoken

npm init -y
npm install express mongoose jsonwebtoken bcryptjs dotenv