Description: Write a function named isUpperCase that accepts a string and returns true or false to judge if the first letter of the string is uppercase, if yes return true, if no return false
Note: Don't use built-in function toUpperCase()
function isUpperCase(str) {
}
console.log(isUpperCase("abcd")); // false
console.log(isUpperCase("Abcd")); // true
console.log(isUpperCase("ABCD")); // true
console.log(isUpperCase("aBCD")); // false
Answer:
function isUpperCase(str) {
if (str[0] >= "A" && str[0] <= "Z") return true;
return false;
}
Reflection:
The key is to know the comparison of alphabetical order could be higher or lower in both uppercase and lowercase letters.
For example:
A: 65, B:66, C:67
B > A, C > B and so on...
Another answer:
function isUpperCase(str) {
return str[0] >= "A" && str[0] <= "Z";
}