JavaScript: Building strings with loops

Loops also allow you to generate strings. It's a common task for web development. It's merely basic aggregation using interpolation or concatenation.

One especially popular task among interviewers is to do a string reversal. There are lots of ways to solve it, but the most basic is by iterating each character. Have a look at how this function works:

reverse('Hexlet'); // telxeH

The general idea of the reversal is that you take characters one by one from the beginning of the string and then connect them in reverse order. Sounds like a piece of cake. Now let's examine it:

const reverse = (str) => {
  let i = 0;
  // A neutral element in terms of strings is an empty string
  let result = '';
  while (i < str.length) {
    // Connect it in reverse order
    result = `${str[i]}${result}`;
    // Same through concatenation
    // result = str[i] + result;
    i = i + 1;
  }

  return result;
};

const name = 'Bran';
reverse(name); // 'narB'
// Testing neutral element
reverse(''); // ''

https://replit.com/@hexlet/js-basics-iteration-over-strings

Perhaps the only tricky part here is getting a feel of how the string itself is built. Since each next character is attached to the resulting string on the left, the string ends up reversed.

Instructions

Write the function even() that returns a new string consisting of even characters from the original string