Query String Parser: Read and Decode URL Parameters Correctly
Parsing query strings by hand is error-prone. Learn how URLSearchParams, qs, and other libraries handle arrays, repeated keys, nested objects, and encoding.
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Tags: url, developer-tools, javascript
Query String Parser: Read and Decode URL Parameters Correctly Query strings look simple — just pairs separated by . But correctly parsing them involves handling plus signs, percent-encoding, duplicate keys, empty values, and keys without values. Get any of these wrong and you'll decode user data incorrectly, silently. Plus Sign vs. : The Space Encoding Distinction This is the most common source of incorrect decoding. * (HTML forms, the default for ): spaces are encoded as . RFC 3986 percent-encoding (general URIs): spaces are encoded as . The has no special meaning. Rule of thumb: Use to parse. Only use if you're parsing a custom query format that doesn't use form encoding. --- Duplicate Keys RFC 3986 says nothing about duplicate keys — different frameworks handle them differently.…
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