Convert URL parameters to object

JavaScript

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

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" }