JavaScript Day 6 — Mastering JavaScript Basics: A Comprehensive Guide for Interview Preparation

100 Days of JavaScript Interview Prep: A Beginner’s Journey

Welcome to Day 6–100 Days of JavaScript Interview Prep: A Beginner’s Journey

Join us as we document a 100-day adventure filled with learning, practice, and growth

DAY 6 (March 28, 2024) —Continuing Most Common String Manipulation Interview Questions

Note if someone wants to try online while reading :)

Can explore below online javascript Playground — Happy Coding!

Online New JavaScript Playground with live changes

We will use online JavaScript Compiler today to run all examples of questions

Question 1 — Write a function to convert a given string to title case?

Tips : ask all permutation and combination of the requirements

Considering here —

a) Converting to uppercase the first letter of every word in a sentence, and the rest of other ones remain in lowercase.

Refer Day 5 for built-in method description and usage with examples in detail

Answer :

let str = 'my pEt nAme is cuFFU' 

str.toLowerCase();
console.log(str.toLowerCase()) // all in lowercase 
// split 
str.toLowerCase().split(' ') 

console.log(str.toLowerCase().split(' ')) // array split

// now add loop and substring

const newstr=str.toLowerCase().split(' ').map((w=>{
  return (w.charAt(0).toUpperCase() + w.substring(1))
})).join(' ')

// slice 

const newstr1=str.toLowerCase().split(' ').map((w=>{
  return (w.charAt(0).toUpperCase() + w.slice(1))
})).join(' ')

// answer

console.log(newstr)
console.log(newstr1)

Tip : Now find the difference between substring and Slice — Reader’s contributions

Provide comments which is best to use and why :). Happy coding

Other Methods -

We can also use reduce, for loop methods please try and provide solutions in comments.

We will add all solutions here as contributors and make our page more engaging :)

Question 2 — Check if a String is Palindrome or Not ?

Tip — Always ask the requirement if hearing first-time, some words.

Ask for Clarification: Politely ask the interviewer to clarify the question if you don’t understand it fully.

Answer :

What is Palindrome ?

A palindrome is a word, number, phrase, or other sequence of symbols that reads the same backwards as forwards.

For example : radar, madam or racecar etc

let mystr = 'radar' // Step 1
mystr.split('') // convert to array // Step 2 
mystr.split('').reverse() // reverse the string // Step 3 
mystr.split('').join() // join the array 
console.log(mystr.split('').reverse().join(' '))
// final code 

Final Code

function isPalindrome(str){
  const reserved = str.split('').reverse().join('');
  return reserved === str
}
const mystr = 'radar'
console.log(isPalindrome(str)); // true 

const mystr = 'radar1'
console.log(isPalindrome(str)); // false

Question 3 — Write a code to check if two given strings are anagrams of each other ?

Answer:

What is anagram ?

A word or phrase, the letters of which can be rearranged into another word or phrase.

Anagrams: bare/bear, reed/deer, calm/clam, ales/seal, toga/goat, hear/hare, aunt/tuna, paws/wasp, flow/wolf

let str1= 'silent'
let str2='listen'
// Step 1 str1.split('') // convert to array 
// Step 2 - sort array
// Step 3 - join 
const word1 = str1.split('').sort().join(''); 
const word2 = str2.split('').sort().join('');
console.log(word1 ,'',word2)
// output 
eilnst
eilnst

Final Code

function isAnagram(str1, str2) {
    const sortStr1 = str1.split('').sort().join('');
    const sortStr2 = str2.split('').sort().join('');
    return sortStr1 === sortStr2;
}
console.log(isAnagram('radar', 'darar')); 
// Output: true

Question 4 — Write a function to check if a given substring exists within a larger sentence.

Answer :

Before diving into the solution, it’s essential to understand why we utilize certain built-in methods.

includes() Method

The includes() method of String values performs a case-sensitive search to determine whether a given string may be found within this string, returning true or false as appropriate.

const sentence = 'i love painting.';
const word = 'painting';
str.includes(word)
console.log(
  `The word "${painting}" ${
    sentence.includes(word) ? 'is' : 'is not'
  } in the sentence`,
);

// The word "painting" is in the sentence

Final Code

function hasWordInSentence(sentence, word) {
    return sentence.includes(word);
}
console.log(hasWordInSentence('hello friend', 'friend')); // Output: true

Question 5 — Write a function to replace all occurrences of a substring/word within a string/sentence with another substring/word.

Answer :

Before diving into the solution, it’s essential to understand why we utilize certain built-in methods.

Split()

The split() method of String values takes a pattern and divides this string into an ordered list of substrings by searching for the pattern, puts these substrings into an array, and returns the array.

const myString = "this is my home";
const resultArr = myString.split('home'); // home with -
console.log(resultArr.join("-")); // home replaced with -
final output // this is my -

Step 1 Word/Substring by first passing in the substring to be replaced in the split() method

Step 2 using the join() method to join the returned array with the new substring/word.

Note — The split() method searches for the passed-in separator argument in the string.

Final Code

function replaceWord(sentence, oldWord, newWord) {
    return sentence.split(oldWord).join(newWord);
}
console.log(replaceWord('hello my name is tom', 'tom', 'cat'));

//hello my name is cat

String manipulation is indeed a vast topic with huge possibilities.

We can continue exploring more examples over the next few days.

Happy learning :)

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Cheers, Kirti Kaushal

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