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  5. decodeURIComponent()
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decodeURIComponent()

Baseline Widely available

This feature is well established and works across many devices and browser versions. Its been available across browsers since July 2015.

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

In this article

Try it

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")); // 
// Expected output: false

Syntax

js
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

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 decodeURI(). It decodes all escape sequences, including those that are not created by encodeURIComponent, like -.!~*'().

Examples

Decoding a Cyrillic URL component

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

Catching errors

js
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.

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

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

Specifications

Specification
ECMAScript 2027 LanguageSpecification
# sec-decodeuricomponent-encodeduricomponent

Browser compatibility

See also

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