decodeURIComponent()

The decodeURIComponent() function decodes a Uniform Resource Identifier (URI) component previously created by {{jsxref("encodeURIComponent()")}} or by a similar routine.

function containsEncodedComponents(x) {
  // ie ?,=,&,/ etc
  return decodeURI(x) !== decodeURIComponent(x);
}

console.log(containsEncodedComponents("%3Fx%3Dtest")); // ?x=test
// Expected output: true

console.log(containsEncodedComponents("%D1%88%D0%B5%D0%BB%D0%BB%D1%8B")); // шеллы
// Expected output: false

Syntax

js-nolint

decodeURIComponent(encodedURI)

Parameters

encodedURI
- : An encoded component of a Uniform Resource Identifier.

Return value

A new string representing the decoded version of the given encoded Uniform Resource Identifier (URI) component.

Exceptions

{{jsxref("URIError")}}
- : Thrown if encodedURI contains a % not followed by two hexadecimal digits, or if the escape sequence does not encode a valid UTF-8 character.

Description

decodeURIComponent() is a function property of the global object.

decodeURIComponent() uses the same decoding algorithm as described in {{jsxref("decodeURI()")}}. It decodes all escape sequences, including those that are not created by {{jsxref("encodeURIComponent")}}, like -.!~*'().

Examples

Decoding a Cyrillic URL component

decodeURIComponent("JavaScript_%D1%88%D0%B5%D0%BB%D0%BB%D1%8B");
// "JavaScript_шеллы"

Catching errors

try {
  const a = decodeURIComponent("%E0%A4%A");
} catch (e) {
  console.error(e);
}

// URIError: malformed URI sequence

Decoding query parameters from a URL

decodeURIComponent() cannot be used directly to parse query parameters from a URL. It needs a bit of preparation.

function decodeQueryParam(p) {
  return decodeURIComponent(p.replace(/\+/g, " "));
}

decodeQueryParam("search+query%20%28correct%29");
// 'search query (correct)'