JavaScript Day 7— Mastering JavaScript Basics: A Comprehensive Guide for Interview Preparation

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

Welcome to Day 7–100 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 7 (March 29, 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 : How can we check if a string is empty or not?

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

1. trim() Method -values removes whitespace from both ends of this string and returns a new string, without modifying the original string.

function isEmptyString(str) {
    return str.trim().length === 0;
}


console.log(isEmptyString(""));        // true
console.log(isEmptyString("Hello"));   // false
console.log(isEmptyString("   "));     // true (since trimmed length becomes 0)

Without Trim Output

function isEmptyString(str) {
    return str.length === 0;
}

console.log(isEmptyString(""));        // true
console.log(isEmptyString("Hello"));   // false
console.log(isEmptyString("   "));     // false (since trim is removed)

Tip : Other Trim method’s trimEnd and trimStart

Please try below method to identify the difference how both works and what difference of results.

Question 2 : Write a function to remove all whitespace characters from a string ?

const inputString = ‘hello world\n\tHow are you?’

Answer :

Method 1 — Regular Expression

const inputString = 'hello \n\tHow are you?'

// Example 1 
console.log(inputString.replace(/\s/g,''));

Method 2 : Using Split and Join()

const inputString = 'hello \n\tHow are you?'
console.log(inputString.split(/\s+/).join(''));

Question 3 : Write a function to count the number of vowels in a given string /sentence ?

const mybestword= “my best world is my home only”

Answer :

Method 1 — Simple For loop

const sentence="my best world is my home only";
const vowels = ['a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'];
let count = 0 ;
for(let character of sentence){
// check character is a vowels 
  if(vowels.includes(character)){
      count++;
    }
}
console.log(count);

Method 2 Regular Expression

const mybestword= "my best world is my home only"
const vowelRegex = /[aeiou]/gi;
const matches = mybestword.match(vowelRegex);
const count = matches ? matches.length : 0;
console.log(count)

Question 4:Write a code to truncate a string if it’s longer than maximum length ?

Consider maximum length === 10

Answer :

const sentence = "my world is my home";
const maxLength = 10
sentence.length // calculate length first
const tt= sentence.length > maxLength ? sentence.slice(0,maxLength) + '..' : sentence;
console.log(tt); // truncated string
console.log(sentence); // orignal string

Question 5 : How to remove duplicates words from sentences ?

Answer :

Assignment to my all coder friends , please add comments for your answers :)

Assignment for our technical readers to find the answer for our audience

Happy coding :)

We will continue with our next section Arrays and Javascript Data Type in our next week April 1st to April 7th ,2024 ..

Stay Tuned and Happy learning :)

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