Percent-encode text for a query string, or decode a percent-encoded string back to text.
Encoding uses encodeURIComponent, so spaces become %20 and reserved characters such as & and = are encoded. Decoding reverses a valid percent-encoded string.
The encoder escapes every character that is not an unreserved URL character. Use it on one component, such as a query value, not on a full URL you want to keep readable.
The decoder rejects a % that is not followed by two hex digits. A plus sign is left as a plus sign. It is not treated as a space, because that convention belongs to HTML forms, not to percent-encoding.
Choose encode when you are building a query value.
Choose decode when you already have a percent-encoded string.
Encode the value only. Leave the ? and & that separate the query in place.
a%20b
Encoding an entire URL, including https://, and then wondering why it no longer opens.
No. A space becomes %20. A plus is encoded as %2B.
No. Encoding the scheme and the slashes will hide the structure of the URL.