Query string <-> JSON

Convert a URL query string to a JSON object or back, with repeated keys folding into an array. Runs on your device, nothing is uploaded.

Query string <-> JSON reads a URL query string into a JSON object, folding a repeated key into an array of every value seen, or runs the reverse with URLSearchParams. Converting to a query string refuses a top-level array or scalar. An array on the JSON side becomes a key repeated once per element, never one list value.

Questions

How are repeated keys handled?

They fold into a JSON array of every value seen for that key, in the order they appeared in the query string.

What does json-to-qs require?

A JSON object at the top level; an array or scalar there is refused.

How is an array value on the JSON side encoded?

As one repeated key, appended once per array element, rather than a single encoded list value.

Does it strip a leading ? or #?

Yes, either is stripped before parsing. A pasted URL fragment therefore works as it is, without trimming it first.

What handles the encoding and decoding?

The browser's own URLSearchParams, the same parser a page uses, so plus signs and percent escapes follow the web rules.

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