review.md

Javascript Review and Practice

type conversion and string concatenation in JavaScript.

1. Sum an integer and a string representation of an integer.
2. Sum a floating-point number and a string representation of a floating-point number.
3. Concatenate two strings.

Here is how to approach each one:

1. To sum the integer and the string representation of an integer, we first need to convert the string to an integer. We can use the built-in JavaScript function parseInt() for this purpose. parseInt() takes a string as an argument and returns its integer representation.

2. To sum a floating-point number and a string representation of a floating-point number, we'll use the parseFloat() function, which is similar to parseInt(), but it's used for floating-point numbers (numbers with decimal points).

3. To concatenate the two strings, we can simply use the + operator. This operator, when used with strings, joins them together.

Now, let's fill in the missing parts of your code:

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 + parseInt(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 + parseFloat(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);
}

Now, when performOperation() is called with the second set of values, it will print the desired outputs. It's important to note that JavaScript has dynamic typing, which means that a variable can be of any type and can be changed. However, when performing operations, we need to make sure that the types are compatible or explicitly convert them to a compatible type, as we did in this problem.

Vowels and Consonants

implement a function that prints all vowels in a given string first, each on a new line, in the order they appear in the string, and then does the same for consonants.

This is a great opportunity to understand control flow in JavaScript with loops and conditional statements. Here's how you could implement this function:

function vowelsAndConsonants(s) {
    let vowels = 'aeiou';
    let consonants = '';

    for(let i = 0; i < s.length; i++) {
        if(vowels.includes(s[i]))
            console.log(s[i]);
        else
            consonants += s[i];
    }

    for(let i = 0; i < consonants.length; i++)
        console.log(consonants[i]);
}

Here's a step-by-step breakdown of the code:

1. Define the vowels in a string for comparison.

2. Initialize an empty string consonants to hold the consonants in s.

3. Loop over each character in the input string s. If a character is included in the vowels string, we immediately print it out. If not, we add it to the consonants string.

4. After handling all the vowels, loop over the consonants string and print each character.

Remember, strings in JavaScript are iterable, like arrays. The includes() method checks if the string contains a certain character, returning true if it does, false otherwise. The += operator is used to concatenate strings.

Lastly, it's important to note that we use let to declare variables in modern JavaScript, as var has some peculiarities that can lead to unexpected results. The variable i needs to be declared and initialized within the loop.