DEV Community: Kiran Kamath

What is CORS 🤔?

Kiran Kamath — Fri, 02 Jan 2026 11:07:04 +0000

Ever faced an issue while making a fetch call saying that it is a CORS issue.
This is probably due to client saying that request to server belonging to another domain could not be made.
CORS actually stands for Cross Origin Resource Sharing.
By default, in all browsers request made from a client having domain to server belonging to same origin is allowed i.e. Same Origin requests are allowed.
example:- request from www.xyz.com/create to server having origin as www.xyz.com is allowed by browser.
This is done to prevent unknown source from making a request and corrupting the system i.e. for security purposes.
But if the browser itself allows a client from another origin to make request, based on the headers provided by server , then we can make this cross origin requests.
Every request made from client end has a header property called as Origin.
When client sends the request , server will send a header in response stating what all cross origin requests are allowed by specifying it in the property :- Access-Control-Allow-Origin.
So the browser will check the response from server and checks if the property Access-Control-Allow-Origin has the origin name specified in it.
In case if the request is not a normal request i.e. is request type is not GET or POST , then a special request is sent from the server first called as Preflight Request.
So this preflight request sent from server will have only headers and no resources , it contains headers such as Access-Control-Allow-Origin , Access-Control-Allow-Methods.
Based on this request from the server , the client will make a new request for resources to the server.

[Boost]

Kiran Kamath — Fri, 02 Jan 2026 07:31:37 +0000

Lydia Hallie

Jul 27 '20

✋🏼🔥 CS Visualized: CORS

#tutorial #webdev #security

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Comments 87

9 min read

Caesar's Cipher (FreeCode Camp Solution)

Kiran Kamath — Fri, 31 Dec 2021 14:32:42 +0000

I recently came across a free code camp problem while solving JavaScript Algorithms and Data Structures certification.

*Problem Statement *:

One of the simplest and most widely known ciphers is a Caesar cipher, also known as a shift cipher. In a shift cipher the meanings of the letters are shifted by some set amount.

A common modern use is the ROT13 cipher, where the values of the letters are shifted by 13 places. Thus A ↔ N, B ↔ O and so on.

Write a function which takes a ROT13 encoded string as input and returns a decoded string.

All letters will be uppercase. Do not transform any non-alphabetic character (i.e. spaces, punctuation), but do pass them on.

Example : rot13("SERR PBQR PNZC") should decode to the string FREE CODE CAMP

Solution :

Take an empty array & store the string passed as arguments by using String split method.
example : let str = "An Apple"; str.split(''); this will give the result as ['A', 'n', ' ', 'A', 'p', 'p', 'l', 'e'];
Iterate the array using for loop
Inside the loop , take the ASCII char code of the first index and store it in a variable.
Check if the ASCII value lies between 65 and 90 i.e Capital alphabets.
If condition is true , check if ASCII value is greater than 77 i.e greater than 'M' , if it is true then subtract 13 from the ascii value , else if it is less than 77 than add 13 to the ascii value.
Now we need to replace character at that index with the corresponding new ASCII code obtained from step 5 using splice and String.fromCharCode
After the entire loop is completed we need to join the array using the join method.

Check out the final code below.

function rot13(str) {
  let charCode = 0;
  let strArr = [];
  strArr = str.split(""); // split the string into array
  for (let i = 0; i < strArr.length; i++) {
    charCode = strArr[i].charCodeAt();
    if (charCode >= 65 && charCode <= 90) {
      if (charCode > 77) {
        charCode = charCode - 13;
      }
      else {
        charCode = charCode + 13;
      }

      strArr.splice(i,1,String.fromCharCode(charCode));
    }
  }
  return strArr.join('');
}

rot13("SERR PBQR PNZC");

Here is the link for the problem : https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher