Convert URL parameters to object

JavaScript version

const getUrlParams = (query) => Array.from(new URLSearchParams(query)).reduce((p, [k, v]) => Object.assign({}, p, { [k]: p[k] ? (Array.isArray(p[k]) ? p[k] : [p[k]]).concat(v) : v }), {});

TypeScript version

const getUrlParams = (query: string): Record<string, string> => (
    Array.from(new URLSearchParams(query)).reduce((p, [k, v]) => Object.assign({}, p, { [k]: p[k] ? (Array.isArray(p[k]) ? p[k] : [p[k]]).concat(v) : v }), {} as Record<string, string>)
);

Examples

getUrlParams(location.search); // Get the parameters of the current URL

getUrlParams('foo=Foo&bar=Bar'); // { foo: "Foo", bar: "Bar" }

// Duplicate key
getUrlParams('foo=Foo&foo=Fuzz&bar=Bar'); // { foo: ["Foo", "Fuzz"], bar: "Bar" }