Check if a value is base64 encoded

Test standard, padded base64.

JavaScript Version 1.0.0 · MIT · .md

function isBase64(value) { return /^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/.test(value); }

Input & expected output

"SGVsbG8="

true

The edge case

"SGVsbG8"

false

Know the limits

• Unpadded and URL-safe (- _) variants fail. Oveyon expects standard base64 for attachment content.

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.