Check if a string is upper case

Compare a string with its uppercase form.

JavaScript Version 1.0.0 · MIT · .md

function isUpperCase(text) { return text === text.toUpperCase(); }

Input & expected output

"SMTP"

true

The edge case

"8812"

true

Know the limits

• A string without letters is unchanged by toUpperCase, so it counts as upper case, as the edge case shows.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Check whether all values are equal — Compare every item with the first using Object.is.
• Check whether an object is empty — Check for own enumerable string keys on a JSON object.
• Check whether an integer is even — Test parity for safe integers, including zero and negative values.