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Javascipt Interview Question and Answers - 2

In this article, I am going to take 3 question which are frequently asked in Javascript interviews. These questions are somewhat linked with the concept of reversing string. These are asked to check the logical ability and approach.
Give someone a program, you frustrate them for a day; teach them how to program, you frustrate them for a lifetime.
Let start with an easy one
Q1. Write a program to reverse the string/word.e.g. if input is 'india', the output should be 'aidni'.
Condition is, the solution should be with minimal lines of code.

So pause for a moment, think about it and them reach out to the solution.

To solve this problem, we need to think, how we can reverse the string, do we have any in built function to reverse a string? Or should we loop through each character of string from last and assign to new string? Or any other approach?

We don't have any built-in function like reverse for a string but we do have for array, Can we make a string to array? Yes we can by splitting the string using split(''). So the problem solved.
This solution should work

1.    function reverseString(str) {
2.         return str.split('').reverse().join('');
3.    }

We can also write this solution using ECMAS 6 arrow function;

var reverseString = (str) => str.split('').reverse().join('')

Boom!!

Now lets move to second problem
Q. Write a program to check if the given string is palindrome or not.

For this we just need to modify and add one condition in our last program.i.e. test if reverse string and input string are same or not

var isPalindrome = (str) => str === str.split('').reverse().join('')

That's it we got the solution.

Let's move to more challenging problem

Q. Write a program to find the largest palindrome and its length in a given string.
Note: There can be more than one palindrome words in a string, we need the largest one.
e.g. str = 'ahanahaikmalayalamkkm' in this we have palindromes like malayalam, ahanaha, kmalayalamk, etc but largest is kmalayalamk.

We can actually need our last solution as a part of this solution.
Here I have tried to solve it using Dynamic programing.

var obj = {
       largest : 0,
       largestPalindrome: ''

      }
function largestPalindrome(fullStr){
       if(isPalindrome(fullStr)){ // use isPalindrome we wrote
           if(fullStr.length > obj.largest){
                  obj.largest = fullStr.length;
                  obj.largestPalindrome = fullStr;
           }
        } else {
           largestPalindrome(fullStr.substr(0,fullStr.length - 1));
           largestPalindrome(fullStr.substr(1,fullStr.length));
         }
 }

Try converting this function using arrow function.

Thank you!!

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In this article we are going to discuss 2 javascript interview question and their answers.These questions are highly asked in the Javascript interviews.

Disclaimer: - You might have different solution working with all test cases for both the problems.

So lets discuss the first question.This question is to test your ability in terms javascript object knowledge and your logical thinking.

Q1. You have been given a nested object "Person" which has one of the property as "password".Write a generic function to change the value of all the "password" property to "*****". Object is nested and may contain other object with property "password" and so on. Here is a sample object.

var Person = {
     name: 'Alex',
     age : 40,
    password : 'abc',
    x : {
       name : 'Chris',
       password: 'abcd',
       y : {
          name : 'Mike',
          password: 'abcd',
         },
     }
.
.
}

Before we …