Palindrome in JavaScript
Last Updated :
07 Dec, 2023
We will understand how to check whether a given value is a palindrome or not in JavaScript. A palindrome is a value that reads the same from backward or forward.
To perform this check we will use the following approaches:
Approach 1: Using for loop (efficient approach)
- Iterate over the string from forward and backward direction
- Check if the character match
- Return false for the first character that does not match
- Return true if all the comparisons are performed and the characters match
Example: This example implements the above approach.
Javascript
function isPalindrome(str) {
let j = str.length - 1
for (let i = 0; i < str.length / 2; i++) {
if (str[i] != str[j]) {
return false ;
}
j--;
}
return true ;
}
let str1 = "racecar" ;
let str2 = "nitin" ;
let str3 = "Rama" ;
console.log(isPalindrome(str1));
console.log(isPalindrome(str2));
console.log(isPalindrome(str3));
|
Approach 2: Using for loop-II
- Initialize a variable and store the reverse of the value in it using for loop
- Compare the original value with the reversed value
- If both values are equal return true else return false
Example: This example implements the above approach.
Javascript
function isPalindrome(str) {
let rev = "" ;
for (let i = str.length - 1; i >= 0; i--) {
rev += str[i];
}
if (rev == str) {
return true
} else {
return false ;
}
}
let str1 = "racecar" ;
let str2 = "nitin" ;
let str3 = "Rama" ;
console.log(isPalindrome(str1));
console.log(isPalindrome(str2));
console.log(isPalindrome(str3));
|
- Use inbuilt string methods like split() to split the string into characters array
- Reverse the array using reverse() method
- Join the array into a string using join() method
- Store this value inside another variable
- Compare the values and return true if both are equal
Example: This example implements the above approach on string
Javascript
function isPalindrome(str) {
let rev = str.split( "" ).reverse().join( "" );
if (rev == str) {
return true
}
return false
}
let str1 = "racecar" ;
let str2 = "nitin" ;
let str3 = "Rama" ;
console.log(isPalindrome(str1));
console.log(isPalindrome(str2));
console.log(isPalindrome(str3));
|
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