Check if a URL is absolute

JavaScript version
const isAbsoluteUrl = (url) => /^[a-z][a-z0-9+.-]*:/.test(url);
TypeScript version
const isAbsoluteUrl = (url: string): boolean => /^[a-z][a-z0-9+.-]*:/.test(url);
Examples
isAbsoluteUrl('https://1loc.dev'); // true
isAbsoluteUrl('https://1loc.dev/foo/bar'); // true
isAbsoluteUrl('1loc.dev'); // false
isAbsoluteUrl('//1loc.dev'); // false