Behzod | IT blog

#interview #js Quyidagi kod qanday natija chiqaradi? var a = { name: 'Vasya' }; var b = { name: 'Vasya' }; console.log(a === b);

Javob: false
Chunki bu 2 xil obyekt hisoblanadi, bu primitiv tip emas

57 views12:10

Behzod | IT blog

#interview #js

Quyidagi kod qanday natija chiqaradi?

function f1(a, b) {
  console.log(a, b);
}

let f2 = f1.bind(null, 'foo');

f2('bar', 'baz');

61 viewsedited 12:29

Behzod | IT blog

#interview #js Quyidagi kod qanday natija chiqaradi? function f1(a, b) { console.log(a, b); } let f2 = f1.bind(null, 'foo'); f2('bar', 'baz');

Javob:

//foo, bar

Chunki bind() orqali f2 nomli yangi funksiya yaratiladi, 'foo' yuqori darajaga ega bo'ladi, bar biz esa 2,3- argument sifatida ketadi

58 views12:31

Behzod | IT blog

#interview #js

Quyidagi kod qanday natija chiqaradi?

let name='rabbit'

function go(){
  let name="Forest"
  console.log(name)
}
name='Alice';
go()

58 views12:38

Behzod | IT blog

#interview #js Quyidagi kod qanday natija chiqaradi? let name='rabbit' function go(){ let name="Forest" console.log(name) } name='Alice'; go()

Javob:

// Forest

Global o'zgaruvchi ta'sir qilmaydi , lokal o'zgaruvchi ishlaydi funksiya ichida

58 views12:39

Behzod | IT blog

#interview #js
Skriptlarni sahifaga ulash (async, defer)

https://telegra.ph/Skriptlarni-sahifaga-ulash-async-defer-02-26

Telegraph

Skriptlarni sahifaga ulash (async, defer)

Zamonaviy vebsaytlarda skriptlar ko'pincha og'irroq bo'ladi HTML ga qaraganda, ularning yuklash hajmi kattaroq, va anchagina vaqt oladi. Qachonki brauzer HTMLni yuklashni boshlasa va <script>...</script> tegiga duch kelsa, brauzer darhol HTML DOM ni yuklashni…

63 viewsedited 02:51

Behzod | IT blog

#interview #js

Quyidagi funksiyani yarating?

add(2, 5); // Output: 7
add(2)(5); // Output: 7

Javob:

const add = (a, b) => {
  if (b !== undefined) return a + b;
  return c => a + c;
};

2-yechim:

function sum(a) {
  return function (b) {
    return a + b; // takes "a" from the outer lexical environment
  };
}

Yanada qiyinrog'i:

console.log(sum(1)(2).toString()); // 3
console.log(sum(1)(2)(3).toString()); // 6
console.log(sum(5)(-1)(2).toString()); // 6
console.log(sum(6)(-1)(-2)(-3).toString()); // 0
console.log(sum(0)(1)(2)(3)(4)(5).toString()); // 15


function sum(a) {
  let currentSum = a;

  function nextSum(b) {
    currentSum += b;
    return nextSum;
  }

  nextSum.toString = function() {
    return currentSum;
  };

  return nextSum;
}



function sum(a) {
  if (arguments.length == 2) {
    return arguments[0] + arguments[1];
  } else {
    return function (b) {
      return a + b;
    };
  }
}

console.log(sum(2, 3)); // Outputs 5sds
console.log(sum(2)(3)); // Outputs 5

62 viewsedited 05:33

Behzod | IT blog

#interview #js

Kengaytmani topadigan kod yozing.
Masalan:

getExtension("ferrf.ferf.fe.exe") // exe

Javob:

const getExtension = (fileName)=>{
if(typof filename !== 'string')
{
throw new Error('Invalid type')
}

const parts = filename.split(' .')
return parts.length == 1 ? null :parts[parts.length-1]
}

56 viewsedited 06:30

Behzod | IT blog

#interview #js
Quyidagi divlar jamlanmasining eng quyi chuqurligini toping?

 <div id="app">
      <div>
        <div>
          <div></div>
        </div>
      </div>
      <div>
        <div>
          <div>
            <div></div>
          </div>
        </div>
      </div>
    </div>

Javob:

const app = document.querySelector('#app');

const treeDepth = (divel, currentLevel) => {
  if (divel.children.length === 0) return currentLevel;
  currentLevel += 1;
  let maxDepth = currentLevel;
  Array.from(divel.children).forEach(element => {
    maxDepth = Math.max(treeDepth(element, currentLevel), maxDepth);
  });
  return maxDepth
};
console.log(treeDepth(app, 0));

60 views08:57

Behzod | IT blog

#interview #js

1. Nuxt js va Vue js farqi
2. SSR nima
3. Child componentdan Parentga
4. Vue js lifecycle hooklar sanang

54 views04:49

Behzod | IT blog

#interview #js

function reduce(arr, callback, initVal) {
  let acc = initVal === 'undefined' ? 'undefined' : 0;
  for (let i = 0; i < arr.length; i++) {
    if (acc !== 'undefined') {
      acc = callback(acc, arr[i], i, arr);
    } else {
      acc = arr[i];
    }
  }
  return acc
}
const numbers=[1,2,3]
console.log(reduce(numbers,function(acc,val){
  return acc+val
},0))

56 viewsedited 07:51

Behzod | IT blog

function map(arr, callback) {
  const newArr = [];
  for (let i = 0; i < arr.length; i++) {
    const result = callback(arr[i], i, arr);
    newArr.push(result);
  }
  return newArr;
}

60 views07:52

Behzod | IT blog

function customSome(callback) {
  for (let i = 0; i < this.length; i++) {
    if (callback(this[i], i, this)) {
      return true;
    }
  }
  return false;
}

Array.prototype.customSome = customSome;

64 views07:54

Behzod | IT blog

function filter(array, callback) {
  const filteredArray = [];
  for (let i = 0; i < array.length; i++) {
    if (callback(array[i], i, array)) {
      filteredArray.push(array[i]);
    }
  }
  return filteredArray;
}

66 views07:55

Behzod | IT blog

Quyidagi funksiyani bir necha marta chaqirish orqali, counterni increment qilishni, yo'li self invoked funksiyadan foydalanish

const add = (function () {
  let counter = 0;
  return function () {counter += 1; return counter}
})();

add();
add();
add();
console.log(add())

58 viewsedited 11:46

Behzod | IT blog

for (var i = 1; i <= 10; i++) {
  function foo(x) {
    setTimeout(() => {
      console.log(x);
    }, 0);
  }
  foo(i);
}

52 views04:20

Behzod | IT blog

function addGlobalEventListener(type, selector, callback, options) {
  document.addEventListener(type, e => {
    if (e.target.matches(selector)) callback(e)
  }, options)
}

addGlobalEventListener("click", ".btn", () => {
  console.log("Clicked Button")
}, { once: true })

55 views13:02

Behzod | IT blog

Nullish operator qattiqroq tekshiradi logical OR(||) operatorga qaraganda

const x = false;
const y = 0;
const z = '';

const a = x || 'default';  // 'default'
const b = y || 'default';  // 'default'
const c = z || 'default';  // 'default'

const d = x ?? 'default';  // false
const e = y ?? 'default';  // 0
const f = z ?? 'default';  // ''

57 views05:47

Behzod | IT blog

Javascript dasturlash tilida bir nechta funksiya turlari bor.

1.Function declaration. Ushbu tur juda keng foydalaniladi. Function declarationda funksiya "function" kalit so'zi bilan boshlanadi va hohlagan nomingizni yozasiz.

Misol:

function myFunction(param1, param2) {
  // Function body
}

2. Function expression.
Bu turdagi funksiyani siz anonim tarzda yaratasiz va biror bir o'zgaruvchiga tenglashtirasiz.

Misol:

const myFunction = function(param1, param2) {
  // Function body
};

3. Arrow functionlar. Bu funksiya turi ES6 versiyada kirgizilgan, Bu funksiyalar doim anonimus bo'ladi.

Misol:

const myFunction = (param1, param2) => {
  // Function body
};

4. Konstrkuturli funksiyalar. Bu turdagi funksiyalar yangi funksiyali obyekt yaratish uchun ishlatiladi

Misol:

const myFunction = new Function("param1", "param2", "return param1 + param2");

58 viewsedited 05:54

Behzod | IT blog

Javascriptda first-class function nima?

First-class function biror bir o'zgaruvchiga tenglashtirilib, boshqa bir funksiya uchun argument sifatida ishlatilinishi mumkin

Misol:

function multiplyByTwo(num) {
  return num * 2;
}

function mapArray(arr, fn) {
  const result = [];
  for (let i = 0; i < arr.length; i++) {
    result.push(fn(arr[i]));
  }
  return result;
}

const numbers = [1, 2, 3, 4];
const doubledNumbers = mapArray(numbers, multiplyByTwo);
console.log(doubledNumbers); // [2, 4, 6, 8]

Bu misolda multiplyByTwo nomli funksiya yaratdik. Shungdek mapArray funksiyani argumentlari, array, va funksiya qabul qiladigan qilib yaratdik. Va natijada biz multiplyByTwo funksiyasini argument sifatida ishlatishimiz va callback qilib chaqirishimiz mumkin

87 views12:13

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