programming-examples/js/String/Input a string and converts upper case letters to lower and vice versa.js

    swapcase = function swapcase(str) {  
            return str.replace(/([a-z]+)|([A-Z]+)/g, function(match, chr) {  
                return chr ? match.toUpperCase() : match.toLowerCase();  
            });  
        }  
    console.log(swapcase('AaBbc'));