sindresorhus/query-string

query-string is a small JavaScript library for reading and writing the part of a URL that comes after the question mark. That part is called a query string, and it carries data like search terms or filter settings. For example, a URL like "example.com/search?term=cat&page=2" has a query string of "term=cat&page=2". The library provides two main operations. Parsing takes a raw query string and converts it into a plain JavaScript object, so each key-value pair becomes a property you can work with in code. Stringifying does the reverse: it takes an object and produces a properly formatted query string you can attach to a URL. Beyond the basics, the library handles several tricky situations that the browser's built-in alternative does not cover as completely. You can control how lists of values are encoded and decoded, choosing between several formats such as repeated keys, comma-separated values, or bracket notation. There are options to automatically convert values to numbers or booleans instead of leaving everything as a string, and a "types" option lets you declare exactly what type each field should have. Sorting of keys can be customized or disabled. The package is installed via npm and works in both browser and server-side JavaScript environments. The README suggests the browser's native URLSearchParams API for simple cases, and positions this library for situations where finer control is needed. The code and model are both under open-source licenses. The repository is maintained by Sindre Sorhus, a prolific open-source author.