 const crypto = require("crypto");
const winEpoch = new Date("01-01-1601 UTC").getTime();

const random = (min, max) => {
  return Math.floor(Math.random() * (max - min + 1) + min);
};

let gLastUSNS = 0;
let gLastTime = 0;
let time = 0;

const getTime = (datetime) => {
  do {
    const winDate = (new Date(datetime).getTime() - winEpoch) * 10000;
    time = winDate + 5748192000000000;
  } while (time === gLastTime && gLastUSNS === 9999);

  if (time === gLastTime) {
    // Если время не изменилось, за микро- и наносекунды
    // возьмем предыдущее значение плюс один
    gLastUSNS++;
  } else {
    // Если время изменилось, за микро- и наносекунды возьмём 0.
    gLastUSNS = random(1, 10000);
    // и запомним значение времени
    gLastTime = time;
  }
  time += gLastUSNS;
  return time;
};

const calcCtrl = (uuid) => {
  let pos = 0;
  let index = 1;
  let sum = 0;
  while (uuid[pos]) {
    const c = uuid[pos++];
    // если символ - десятичная цифра
    if (/\d/.test(c)) {
      // увеличение суммы и индекса
      sum += parseInt(c, 10) * index++;
    }

    // если символ - шестнадцатеричная цифра
    if (/[a-f]/i.test(c)) {
      sum += parseInt(c, 16) * index++;
    }
    // если значение индекса превысило 10, сбрасываем индекс в 1
    if (index > 10) index = 1;
  }

  const r = sum % 16;
  // возврат результата в виде контрольного символа
  if (r < 10) {
    return r;
  }
  return r.toString(16);
};

const isValid = (data) => {
  const res = data.match(/^([0-9a-f]{8}-[0-9a-f]{4}-1[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12})-([0-9a-f]{1})$/);
  if (!res) return false;
  const [, uuid, cs] = res;
  if (!uuid && !cs) {
    return false;
  }
  return calcCtrl(uuid) == cs;
};

const bin2Hex = (bin) => {
  const dec = parseInt(bin, 2);
  const hex = dec.toString(16).padStart(4, "0");
  return hex;
};

const gClockSeq = Buffer.alloc(14, crypto.randomBytes(14).readUInt32BE(0, true).toString(2));
const generate = (datetime = new Date()) => {
  const gt = getTime(datetime);

  const buff = Buffer.alloc(57, gt.toString(2));

  const version_time_hide = Buffer.from(buff.buffer, 0, 9); // Из-за смещения 3ех нулей беру 9 байт

  const clockseq_low = Buffer.from(gClockSeq.buffer, 6);
  const variant_clockseq_high = Buffer.from(gClockSeq.buffer, 0, 6);

  const time_low = Buffer.from(buff.buffer, 25);

  const time_mid = Buffer.from(buff.buffer, 9, 16);

  const time = {
    time_bin: buff + "",
    time_low: time_low + "",
    time_mid: (time_mid + "").padStart(16, "0"),
    version_time_hide: "0001000" + version_time_hide,
    clockseq_low: `10${variant_clockseq_high.toString("binary")}${clockseq_low.toString("binary")}`,
  };

  const node = Buffer.alloc(6);
  node[0] = crypto.randomBytes(4).readUInt32BE(0, true);
  node[1] = crypto.randomBytes(4).readUInt32BE(0, true);
  node[2] = crypto.randomBytes(4).readUInt32BE(0, true);
  node[3] = crypto.randomBytes(4).readUInt32BE(0, true);
  node[4] = crypto.randomBytes(4).readUInt32BE(0, true);
  node[5] = crypto.randomBytes(4).readUInt32BE(0, true);
  const result = [
    bin2Hex(time.time_low).padStart(8, "0"),
    bin2Hex(time.time_mid),
    bin2Hex(time.version_time_hide),
    bin2Hex(time.clockseq_low),
    node.toString("hex"),
  ].join("-");
  return result + "-" + calcCtrl(result);
};

const toDate = (uuid) => {
  const [, time_low, time_mid, version_time_hide] = uuid.match(/^([0-9a-f]{8})-([0-9a-f]{4})-([0-9a-f]{4})-([0-9a-f]{4})/);

  const bin_version_time_hide = parseInt(version_time_hide, 16)
    .toString(2)
    .replace(/^1000(.+)/, "$1");
  const bin_time_mid = parseInt(time_mid, 16).toString(2).padStart(16, "0");
  const bin_time_low = parseInt(time_low, 16).toString(2).padStart(32, "0");

  const buff = Buffer.alloc(57, `${bin_version_time_hide}${bin_time_mid}${bin_time_low}`);

  const nSec = parseInt(buff.toString("binary"), 2) - 5748192000000000;
  return new Date(nSec / 10000 + winEpoch);
};

const info = (uuid) => {
  const controlNum = uuid.split("-")[5];

  return {
    len: uuid.length,
    valid: isValid(uuid),
    controlNum,
    gClockSeq: parseInt(gClockSeq.toString("hex"), 16),
    datetime: toDate(uuid),
  };
};

module.exports = {
  generate,
  isValid,
  getTime,
  toDate,
  info,
};

const isValidUUID = isValid('c5a8debd-6041-11ea-8180-00155d93bf1a')
console.log(isValidUUID)

created 2 years ago

Javascript Online Compiler

Write, Run & Share Javascript code online using OneCompiler's JS online compiler for free. It's one of the robust, feature-rich online compilers for Javascript language. Getting started with the OneCompiler's Javascript editor is easy and fast. The editor shows sample boilerplate code when you choose language as Javascript and start coding.

About Javascript

Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript is required to design the behaviour of the web pages.

Key Features

Open-source
Just-in-time compiled language
Embedded along with HTML and makes web pages alive
Originally named as LiveScript.
Executable in both browser and server which has Javascript engines like V8(chrome), SpiderMonkey(Firefox) etc.

Syntax help

STDIN Example

var readline = require('readline');
var rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});

rl.on('line', function(line){
    console.log("Hello, " + line);
});

variable declaration

Keyword	Description	Scope
var	Var is used to declare variables(old way of declaring variables)	Function or global scope
let	let is also used to declare variables(new way)	Global or block Scope
const	const is used to declare const values. Once the value is assigned, it can not be modified	Global or block Scope

Backtick Strings

Interpolation

let greetings = `Hello ${name}`

Multi line Strings

const msg = `
hello
world!
`

Arrays

An array is a collection of items or values.

Syntax:

let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);

Example:

let mobiles = ["iPhone", "Samsung", "Pixel"];

// accessing an array
console.log(mobiles[0]);

// changing an array element
mobiles[3] = "Nokia";

Arrow functions

Arrow Functions helps developers to write code in concise way, it’s introduced in ES6.
Arrow functions can be written in multiple ways. Below are couple of ways to use arrow function but it can be written in many other ways as well.

Syntax:

() => expression

Example:

const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
                                    .map(ele => ele ** 2);
console.log(squaresOfEvenNumbers);

De-structuring

Arrays

let [firstName, lastName] = ['Foo', 'Bar']

Objects

let {firstName, lastName} = {
  firstName: 'Foo',
  lastName: 'Bar'
}

rest(...) operator

 const {
    title,
    firstName,
    lastName,
    ...rest
  } = record;

Spread(...) operator

//Object spread
const post = {
  ...options,
  type: "new"
}
//array spread
const users = [
  ...adminUsers,
  ...normalUsers
]

Functions

function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
  console.log(`Hello ${name}!`);
}
 
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar

Loops

1. If:

IF is used to execute a block of code based on a condition.

Syntax

if(condition){
    // code
}

2. If-Else:

Else part is used to execute the block of code when the condition fails.

Syntax

if(condition){
    // code
} else {
    // code
}

3. Switch:

Switch is used to replace nested If-Else statements.

Syntax

switch(condition){
    case 'value1' :
        //code
        [break;]
    case 'value2' :
        //code
        [break;]
    .......
    default :
        //code
        [break;]
}

4. For

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
//code  
}

5. While

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
  // code 
}

6. Do-While

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
  // code 
} while (condition);

Classes

ES6 introduced classes along with OOPS concepts in JS. Class is similar to a function which you can think like kind of template which will get called when ever you initialize class.

Syntax:

class className {
  constructor() { ... } //Mandatory Class method
  method1() { ... }
  method2() { ... }
  ...
}

Example:

class Mobile {
  constructor(model) {
    this.name = model;
  }
}

mbl = new Mobile("iPhone");