Decode a percent-encoded URL component.

JavaScript: decodeURIComponent reverses percent encoding and throws for malformed sequences.

JavaScript snippet.js
console.log(decodeURIComponent("hello%20world%21"));

Expected output EXAMPLE

hello world!

Details

Save as snippet.js and run node snippet.js. Uses built-in Node.js and JavaScript APIs. decodeURIComponent reverses percent encoding and throws for malformed sequences.

Keep in mind

Unlike form decoding, this function does not convert plus signs to spaces.

✓ Verified

Tested on Ubuntu 24.04.5 LTS · · v18.19.1 · nodejs 18.19.1+dfsg-6ubuntu5

Test inputs, results and environment

The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.

Architecture / host kernel
x86_64 / 6.18.54.1-microsoft-standard-WSL2
Snippet identity / locale
uid=65534, gid=65534 (unprivileged) / C.UTF-8
Interpreter invocation
node snippet.js
Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd
Code SHA-256
0c49a36f85c1a844fc40cffac7fe3947b8b445792b8aa1f603f78e6e9a378694
Dependencies
nodejs 18.19.1+dfsg-6ubuntu5

Test input setup

These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.

# No input files required.

Observed standard output

hello world!

Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.