WHATWG URLSearchParams

Elide implements the WHATWG [URL Standard][spec] URLSearchParams global — an ordered list of (name, value) string pairs serialised as application/x-www-form-urlencoded. All operations (append, delete, get, getAll, has, set, sort) and the iterator protocols (entries, keys, values, forEach, default @@iterator) match the spec exactly. A shared iterator prototype inherits from %IteratorPrototype%, so for-of and spread work unmodified.

[spec]: https://url.spec.whatwg.org/#interface-urlsearchparams

Construction

new URLSearchParams()                           // empty
new URLSearchParams("?a=1&b=2")                 // USVString (leading `?` is stripped)
new URLSearchParams([["a", "1"], ["b", "2"]])   // sequence of pairs
new URLSearchParams({ a: "1", b: "2" })         // record<USVString, USVString>

Any non-string, non-sequence, non-record value raises TypeError. A sequence element whose length is not exactly two also raises TypeError, per the spec.

Operations

Method	Returns	Notes
`append(n, v)`	`undefined`	Adds a pair at the end of the list.
`delete(n)`	`undefined`	Removes every pair whose name matches `n`.
`delete(n, v)`	`undefined`	Removes only pairs where both name and value match — spec's optional `value` argument.
`get(n)`	`string \	null`	First value whose name matches, or `null`.
`getAll(n)`	`string[]`	All values in insertion order.
`has(n)`	`boolean`	`true` if any pair with name `n` exists.
`has(n, v)`	`boolean`	`true` if any pair has both name `n` and value `v`.
`set(n, v)`	`undefined`	Replaces the first matching pair's value and drops later duplicates; appends if absent.
`sort()`	`undefined`	Stable sort by name in Unicode code-unit order.
`toString()`	`string`	`application/x-www-form-urlencoded` serialisation.

Attributes

Name	Type
`size`	`unsigned long`

Iteration

URLSearchParams is a pair iterable:

for (const [name, value] of new URLSearchParams("a=1&b=2")) {
  console.log(name, value);
}

entries() — pair iterator (the default).
keys() — name-only iterator.
values() — value-only iterator.
forEach(cb, thisArg?) — imperative iteration; callback is invoked as cb.call(thisArg, value, name, searchParams).

All iterators are live — mutations during traversal (via append, delete, set, or sort) are observable by subsequent next() calls. forEach walks by index and picks up later-added pairs mid-loop.

Encoding

Serialisation uses the application/x-www-form-urlencoded percent-encode set: ASCII alphanumeric plus *, -, ., _ pass through unchanged; space encodes as +; everything else encodes as UTF-8 bytes in %HH form. Parsing reverses the encoding and converts unpaired UTF-16 surrogates to U+FFFD per the WHATWG Encoding Standard.

const sp = new URLSearchParams();
sp.append("k", "hello world");
sp.append("unicode", "тест");
sp.toString();
// → "k=hello+world&unicode=%D1%82%D0%B5%D1%81%D1%82"

Compatibility notes

URLSearchParams is installed as a global on every JavaScript realm in Elide.
The class is fully conformant with WHATWG URL §5; behaviour matches Node.js, Deno, and modern browsers.
Live binding with URL.searchParams is wired when the full WHATWG URL class is also loaded — a standalone URLSearchParams behaves identically without a backing URL.