Moving every alphabet forward by 10 places in JavaScript

Problem

We need to write a JavaScript function that takes a string of English alphabets and shifts every letter forward by 10 positions. When a letter goes past 'z', it wraps around to start again at 'a'.

Example

Following is the code −

const str = 'sample string';
const moveStrBy = (num = 10) => {
    return str => {
        const calcStr = (ch, code) => String
            .fromCharCode(code + (ch.charCodeAt(0) - code + num) % 26);
        const ACode = 'A'.charCodeAt(0);
        const aCode = 'a'.charCodeAt(0);
        return str.replace(/[a-z]/gi, ch => (
            ch.toLowerCase() == ch
            ? calcStr(ch, aCode)
            : calcStr(ch, ACode)
        ));
    };
};
const moveByTen = moveStrBy();
console.log(moveByTen(str));

Output

ckwzvo cdbsxq

How It Works

The solution uses a higher-order function approach:

• moveStrBy() returns a function that shifts characters by the specified number
• calcStr() handles the character shifting with modulo arithmetic to wrap around
• replace() with regex /[a-z]/gi processes all alphabetic characters
• Preserves original case by checking if the character is lowercase or uppercase

Simplified Version

Here's a more direct approach for shifting by 10 positions:

function shiftAlphabetBy10(str) {
    return str.replace(/[a-zA-Z]/g, char => {
        const isLowerCase = char >= 'a' && char 

Rovvy Gybvn


Key Points

• Uses charCodeAt() to get ASCII values and String.fromCharCode() to convert back
• Modulo operator (%) ensures wrapping from 'z' to 'a' or 'Z' to 'A'
• Preserves case and non-alphabetic characters remain unchanged
• The shift value of 10 moves 'a' to 'k', 'b' to 'l', etc.

Conclusion

This alphabet shifting technique uses ASCII arithmetic with modulo operations to create a Caesar cipher-like transformation. The approach efficiently handles case preservation and character wrapping.