Get the value of a param from a URL

Parse an absolute URL and read one query parameter.

JavaScript Version 1.0.0 · MIT · .md

function getParam({ url, param }) { return new URL(url).searchParams.get(param); }

Input & expected output

{
  "url": "https://example.com/unsubscribe?token=abc123&list=news",
  "param": "token"
}

"abc123"

The edge case

{
  "url": "https://example.com/",
  "param": "token"
}

null

Know the limits

• A missing parameter returns null. Repeated parameters return the first value; use getAll for every value.
• Treat tokens from links as credentials: never log them.

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.