JavaScript
const baseUrl = (url) => (url.indexOf('?') === -1 ? url : url.slice(0, url.indexOf('?')))
const baseUrl = (url) => (url.includes('?') ? url.slice(0, url.indexOf('?')) : url)
const baseUrl = (url) => url.split('?')[0]
TypeScript
const baseUrl = (url: string): string => (url.indexOf('?') === -1 ? url : url.slice(0, url.indexOf('?')))
const baseUrl = (url: string): string => (url.includes('?') ? url.slice(0, url.indexOf('?')) : url)
const baseUrl = (url: string): string => url.split('?')[0]
Examples
baseUrl('https://domain.com/path/sub/path?foo=bar&hello=world')