//大写转小写
function manualLowercase(s) {
s.replace(/[A-Z]/g, function(ch) {
return String.fromCharCode(ch.charCodeAt(0) | 32);
});
}
//小写转大写
function manualUppercase(s) {
s.replace(/[a-z]/g, function(ch) {
return String.fromCharCode(ch.charCodeAt(0) & ~32);
});
}
原文：https://www.cnblogs.com/hanhui66/p/9945623.html