everyutil/string/alternateCase.js

A comprehensive library of lightweight, reusable utility functions for JavaScript and TypeScript, designed to streamline common programming tasks such as string manipulation, array processing, date handling, and more.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.alternateCase = void 0;
/**
 * Alternates between lowercase and uppercase for each letter in the string.
 *
 * Example: alternateCase("hello world") → "HeLlO WoRlD"
 *
 * @author @dailker
 * @param {string} str - The input string.
 * @returns {string} The string with alternating case.
 */
function alternateCase(str) {
    let up = true;
    return str.split('').map(c => {
        if (/[a-z]/i.test(c)) {
            const res = up ? c.toUpperCase() : c.toLowerCase();
            up = !up;
            return res;
        }
        return c;
    }).join('');
}
exports.alternateCase = alternateCase;