const isRelative = (path) => !/^([a-z]+:)?[\\/]/i.test(path);
const isRelative = (path: string): boolean => !/^([a-z]+:)?[\\/]/i.test(path);
isRelative('/foo/bar/baz'); // falseisRelative('C:\\foo\\bar\\baz'); // falseisRelative('foo/bar/baz.txt'); // trueisRelative('foo.md'); // true