reverse method
反转字符串
Implementation
String reverse(String text) {
if (isEmpty(text)) {
return '';
}
StringBuffer sb = StringBuffer();
for (int i = text.length - 1; i >= 0; i--) {
var codeUnitAt = text.codeUnitAt(i);
sb.writeCharCode(codeUnitAt);
}
return sb.toString();
}