Encode a URL component strictly

Percent-encode a value, including !'()* that encodeURIComponent leaves alone.

JavaScript Version 1.0.0 · MIT · .md

function encodeStrict(value) { return encodeURIComponent(value).replace(/[!'()*]/g, char => `%${char.charCodeAt(0).toString(16).toUpperCase()}`); }

Input & expected output

"it's (50%) off!"

"it%27s%20%2850%25%29%20off%21"

The edge case

"~-_."

"~-_."

Know the limits

• RFC 3986 unreserved characters (- _ . ~) stay as they are, as the edge case shows. The original also encoded ~, which RFC 3986 leaves unreserved.

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

• Convert Celsius to Fahrenheit — Apply the temperature conversion without rounding the result.
• Convert hex to RGB — Expand #rgb if needed and read the red, green and blue channels.
• Convert URL parameters to object — Read a query string into an object; repeated keys become arrays.