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1. HTML + CSS Related Interview Question

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2. Javascript Related Interview Question

Main Topic

• 🔥 Most High Priority Must have Clear idea
  • Scope
  • Hoisting
  • Closure
  • Curring
  • Event Loop
  • Debouncer
  • Asynchronous js

• High Priority
  • Promises
  • Local vs Session Storage
  • Higher Oder Function (Hoc)
  • Event Bubble + Event Deligation
  • Prototype
  • Event Propogation

• MID Priority
  • Ternary Operators
  • Template Literals
  • Data Types
  • Undefined vs Null
  • Nan vs Null
  • ForEach(), Map() , Filter(), trim(), split(),join(),reverse(),
  • [=== vs ==]
  • Mutable vs unMutatable
  • this keyword
  • Nullish Coalseing Operators
  • Optional Chaining
  • Undefined Hole
  • Lexical environment
  • Callback Hell
  • BOM + DOM

3. JS Probem Solving

String Problems

- Random Number Generator - Basic CRUD - Reverse String - Find Duplicates - Finding Values based on condition

todo:1 [Math Random]

• লুডু খেলায় আমরা কিভাবে ১ থেকে ৬ সংখ্যা randomly print করতে পারি ।

function getRandomNumber(min, max){
    return Math.floor(Math.random() *(max-min +1)) + min;
}

console.log(getRandomNumber(1,6));

// another way
const random1 =((Math.random()*10)+1);
const random2 =Math.floor(((Math.random()*7)));
console.log(random1)  // print 1-6
console.log(random2) // print 1-6

• Get random id or Reverse id

const id = Math.random().toString().split(".")[1];
const id1 =crypto.randomUUID();
const revId = id.split("").reverse().join("");
const revId1 = id1.split("").reverse().join("");

console.log(id," | ",revId)  // 6024356929627508  |  8057269296534206
console.log(id1, " | ",revId1) // 83fdaf7b-ec0b-49f3-b161-0f5c78c81d41  |  14d18c87c5f0-161b-3f94-b0ce-b7fadf38


const  num =12345;
const r =Number(num.toString().split("").reverse().join(""));
console.log(num, "|||" ,r)  // 12345 ||| 54321

• Reverse Sting

let str1 ="bappasaha"
const reverse =str1.split("").reverse().join("");
console.log(str1, "<->",reverse)  // bappasaha <-> ahasappab


let str ="b-a-p-p-a";
console.log(str.split("-")) ;
console.log(str.split("-").join(","));

todo:2- [sort ( ) ] সবার নাম কিভাবে Alphabetically সাজাতে পারি ।

• সবার নাম কিভাবে Alphabetically সাজাতে পারি ।

const std = ["bappa","kaoa","dafda","apple"];
console.log(std.sort());

• How to sort roll number low to high

const rollNumebers = [40, 100, 1, 5, 25, 10];

function myFuc(a,b){
    return a-b;
};
console.log(rollNumebers.sort(myFuc)) // [ 1, 5, 10, 25, 40, 100 ]


//shortcut
const rollNumebers = [40, 100, 1, 5, 25, 10];
console.log(rollNumebers.sort((a,b)=>{return a-b})) // assending
console.log(rollNumebers.sort((a,b)=>{return b-a})) //decending

todo: 3- [filter ( )] find the duplicate and Unique number and string from an array

• find the duplicate number from an array

// const arr = ["bappa", "appa", "cappa", "bappa"];

// const item = arr.forEach((item, index, arr) => console.log("items:",item));
// const d = arr.filter((item, index) => console.log(arr.indexOf(item) !==index));
// const i = arr.filter((item, index) => console.log(arr.indexOf(index)));


const numbers =[1,2,4,5,6,6,1,5,76,,89,76,90,25];

const duplicate =numbers.filter((value,index, array)=>{
    return array.indexOf(value)!==index;
});

console.log(duplicate);


const arr = ["bappa", "appa", "cappa", "bappa"];
const duplicates = arr.filter((item, index) => arr.indexOf(item) !== index);
console.log(duplicates); // Output: ["bappa"]

• find the unique number from an array

const numbers1 =[1,2,4,5,6,6,1,5,76,,89,76,90,25];

const unique =numbers.filter((value,index, array)=>{
    return array.indexOf(value)===index;
});
console.log('---');
console.log(unique);

const arr = ["bappa", "appa", "cappa", "bappa"];
const uniqueItems = arr.filter((item, index) => arr.indexOf(item) === arr.lastIndexOf(item));
console.log(uniqueItems); // Output: ["appa", "cappa"]

todo:-4 How many vowels in sentence

const vowels =["a","e","i","o","u","A","E","I","O","U"];

const countVowel=(sentence)=>{
    let count =0;
    const letters =Array.from(sentence);
    letters.forEach((letter)=>{
        if(vowels.includes(letter)){
            count++;
        }
    })
    return count;

};

console.log(countVowel("I love Bangladesh"));

todo:-5 Leap year or Not

function isLeapyear(year){
    if(year%400 ===0 || ((year %4 ===0) && (year % 100 !==0))){
        console.log(`${year} is Leap year`);
    }
    else 
        console.log('not');
};

isLeapyear(2020);

todo:-6: how many time "bappa" word is used in the sentence and what is the first position where bappa word is used?

This type of problem is solved by using regular expression

1. regular exp er vittore search string ta dibo
2. ig flag ta dibo.
3. jotogulo ans pabo ta ekta array tai array er length tai ans

solve: first position mane search() ta dilei hbe

const sentence ="There is a dreamy boy nameed Bappa.There is a dreamy boy nameed bappa.There is a dreamy boy nameed bappa.There is a dreamy boy."

const matches =sentence.match(/bappa/ig);
const occurances =matches? matches.length : 0;
console.log(matches, occurances)


let position =sentence.search(/bappa/i);
position= position>=0 ? position : "not found";
console.log(position)

todo:7 input: linearSearch(['a','b','c','d','c'], 'c'); output: 2 or 'not found' ; problem: linearSearch() টি function implement করে দেখান ।

function linearSearch(arr,value){

    const length =arr.length;
    for(let i =0; i<length; i++){
        if(arr[i]===value){
            return i;
        }
    }
    return "not found";
}

console.log(linearSearch(['a','b','c','d','c'], 'c'));

todo:8- find out the max big string from an array and show the index of the string

function longestString(names){
    let longestWord ='';
    for(n of names){
        if(n.length > longestWord.length){
            longestWord =n;
        }
    }
    return [longestWord, names.indexOf(longestWord)]

}

const nameArray=['Bappa saha', 'learn with bappa','akash','akash mohajoon','dad'];

console.log(longestString(nameArray));

todo:9- ১ -১০০ পর্যন্ত যেই সংখ্যা গুলো ৩,৫ এবং ৩,৫ উভয় সংখ্যা দিয়ে বিভাজ্য তা বের কর

function fooBar(number){
    
    for (let i =1; i<=number; i++){
        if(i%3===0 && i%5===0){
            console.log(`${i} is fooBar number`);
        }
        else if(i%3===0){
            console.log(`${i} is divied by 3`);
        }
        else if(i%5 ===0){
            console.log(`${i} is divied by 5`)
        }
        else{
            console.log(`${i} is not  divied by 3 or 5`);
        }
    }
}

console.log(fooBar(100))

todo:10- Remove falsy values from array and object

• Array থেকে কিভাবে 'falsy value' খুঁজে বের করে বাদ দিতে পারি?

    falsy values are: 6 types
    false, undefined, null, '', NaN, 0
    solve: using filter()
  

const mixedArr =[
    "bws",
    undefined,
    "learn with bappa",
    0,
    false,
    "",
    "apple",
    null,
    40,
    "k",
    true,
    "Thanks all",
    NaN
];


const trueArray =mixedArr.filter(element=>{
    if(element){
        return true;
    }else{
        return false
    }
})
console.table(trueArray) 


// another way

const  trueArray1 =mixedArr.filter(Boolean)
console.table(trueArray1)

• Object থেকে কিভাবে 'falsy value' খুঁজে বের করে বাদ দিতে পারি?

const obj ={

    a:"bws",
    b:undefined,
    c:"learn with bappa",
    d:0,
    e:false,
    f:"",
    g:"apple",
    h:null,
    i:40,
    j:"k",
    k:true,
    l:"Thanks all",
    m:NaN
};

const trutyObj =function(obj){
    for(let i in obj){
        if(!obj[i]){
            delete obj[i];
        }
    }
    return obj;
}

console.log(trutyObj(obj))

4. Main Topic React Interview

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