HackerRank 10 Days of JS

Author: Doe Hoon LEE

Day 0 : Hello, World!

Task

Use console.log() to print the parameter

function greeting(parameterVariable) {
    // This line prints 'Hello, World!' to the console:
    console.log('Hello, World!');

    // Write a line of code that prints parameterVariable to stdout using console.log:
    console.log(parameterVariable)
}

Day 0 : Data Types

(1) Convert ‘secondInteger’ to an integer(Number type), the sum it with ‘firstInteger’ and print the result on a new line using console.log()

(2) Convert ‘secondDecimal’ to a floating-point number (Number type), the sum it with ‘firstDecimal’ and print the result on a new line using console.log()

(3) Print the concatenation of ‘firstString’ and ‘secondString’ on a new line using console.log()

function performOperation(secondInteger, secondDecimal, secondString) {
    // Declare a variable named 'firstInteger' and initialize with integer value 4.
    const firstInteger = 4;
    
    // Declare a variable named 'firstDecimal' and initialize with floating-point value 4.0.
    const firstDecimal = 4.0;
    
    // Declare a variable named 'firstString' and initialize with the string "HackerRank".
    const firstString = 'HackerRank ';
    
    // Write code that uses console.log to print the sum of the 'firstInteger' and 'secondInteger' (converted to a Number        type) on a new line.
    console.log(firstInteger + Number(secondInteger));
    
    // Write code that uses console.log to print the sum of 'firstDecimal' and 'secondDecimal' (converted to a Number            type) on a new line.
    console.log(firstDecimal + Number(secondDecimal));
    
    // Write code that uses console.log to print the concatenation of 'firstString' and 'secondString' on a new line. The        variable 'firstString' must be printed first.
    console.log(firstString + secondString);
}

Day 1 : Arithmetic Operators

getArea(length, width): Calculate and return the area of a rectangle having sides ‘length’ and ‘width’.

getPerimeter(length, width): Calculate and return the perimeter of a rectangle having sides ‘length’ and ‘width’.

The values returned by these functions are printed to stdout by locked stub code in the editor.

// function calculating area
function getArea(length, width) {
    let area;
    // Write your code here
    area = length * width;
    return area;
}

// function calculating perimeter
function getPerimeter(length, width) {
    let perimeter;
    // Write your code here
    perimeter = 2 * (length + width);
    return perimeter;
}

Day 1 : Functions

Implement a function named factorial that has one parameter: an ineger, n. It must return the value of n!

function factorial(num) {
    let array = [];
    for (let i=num; i > 0; i--) {
        array.push(i);
    };
    return array.reduce(function(a,b) {
        return a * b;
    }, 1);
}

Day 2 : Let and Const

1. Declare a constant variable PI, and assign it the value of Math.PI. You will not pass this challenge unless the variable is declared as a constant and named PI(UPPERCASE)

2. Read a number r, denoting the radius of a circle from stdin.

3. Using PI and r to calculate the area and perimeter of a circle having radius r.

4. Print area as the first line of output and print perimeter as the second line of output.

const r = readLine();
const PI = Math.PI;
// Print the area of the circle:
console.log(PI*(r**2));
// Print the perimeter of the circle:
console.log(2*PI*(r));

Day 2 : Conditional Statements : If-Else

If 25 < score <= 30, then grade = A. If 20 < score <= 25, then grade = B. If 15 < score <= 20, then grade = C. If 10 < score <= 15, then grade = D. If 5 < score <= 10, then grade = E. If 0 < score <= 5, then grade = F.

Day 2 : Loops

Complete the vowelsAndConsonants function.

1. First, print each vowel in s on a new line. The English vowels are a, e, i, o, u, and each vowel must be printed in the same order as it appeared in s.

2. Second, print each consonant (ie., non-vowel) in s on a new line in the same order as it appeared in s.

/*
 * Complete the vowelsAndConsonants function.
 * Print your output using 'console.log()'.
 */
function vowelsAndConsonants(s) {
    const vowels = ["a", "e", "i", "o", "u"];
    for (let i=0; i < s.length; i++) {
        if (vowels.includes(s[i])) {
            console.log(s[i]);
        }
    }
    for (let i=0; i < s.length; i++) {
        if (!vowels.includes(s[i])) {
            console.log(s[i]);
        }
    }
}