URLSearchParams.prototype.keys

Returns an iterator for parameter names.

Example

let params = new URLSearchParams("foo=1&bar=2")
for (let key of params.keys()) {
    key
}

"foo"

let params = new URLSearchParams("a=1&b=2&a=3")
Array.from(params.keys())

["a", "b", "a"]

let iterator = new URLSearchParams("x=y&z=w").keys()
iterator.next().value

"x"