JS Coding Question #2: Reverse a string [Common Question - 3 Solutions]
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Let's Code @frontendengineer

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May 6, 2019

JS Coding Question #2: Reverse a string [Common Question - 3 Solutions]

Publish Date: Aug 25 '21
16 7

Interview Question #2:

Write a function that reverses a string❓🤔

If you need practice, try to solve this on your own. I have included 3 potential solutions below.

Note: There are many other potential solutions to this problem.

Feel free to bookmark 🔖 even if you don't need this for now. You may need to refresh/review down the road when it is time for you to look for a new role.

Code: https://codepen.io/angelo_jin/pen/LYBPrKo

Solution #1: Array methods

  • very simple solution that will utilize array methods to reverse the string. 
function reverseString(str) {
    return str.split("").reverse().join("");
}
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Solution #2: Array forEach

  • will cycle through each characters and push it on the temp variable created one by one in reversed order. 
function reverseString(str) {
    let reversedString = ''

    str.split('').forEach(char => {
        reversedString = char + reversedString
    })

    return reversedString
}
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Solution #3: Array reduce

  • slightly better than second solution above. Will use reduce and add the result to the empty string in reverse. 
function reverseString(str) {
    return str.split('')
        .reduce((prev, curr) => curr + prev, '')
}
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Happy coding and good luck if you are interviewing!

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Comments 7 total

  • Let's Code
    Let's CodeSep 8, 2021

    thanks for the complete solution! definitely appreciate your time adding this in and spreading the knowledge.

    I would be very surprised if I get asked to take unicode character into account in an interview though.

  • Let's Code
    Let's CodeSep 8, 2021

    definitely a good possibility in my opinion. I got asked to code it on my last job but it is not to extreme like accounting for unicode. It was something quick and straight to the point. I imagine myself to not continue the interview if interview would go to this extreme. LOL

    I wrote an article about FIzz Buzz as well, should be in this series and I was shocked to find out he was asked about it on his recent interview.

    Maybe junior level can be asked perhaps?

  • Let's Code
    Let's CodeSep 9, 2021

    I totally agree with you. Might be more accurate to say companies HAVE moved away from FizzBuzz interview questions.

  • Vinayak Phal
    Vinayak PhalAug 13, 2023

    You can use stack concept to reverse the string.

    function reverseString(str) {
  let reverseStr = "";
  let strStack = str.split('');
  while(strStack.length){
    reverseStr+=strStack.pop();
  }
  return reverseStr;
}
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    One more simple solution using length and traversing backwards.

    function reverseString(str) {
  let reverseStr = "";
  for (let i = str.length - 1; i >= 0; i--) {
    reverseStr += str[i];
  }
  return reverseStr;
}
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