const isRelative = (path) => !/^([a-z]+:)?[\\/]/i.test(path);

isRelative('/foo/bar/baz'); // false
isRelative('C:\\foo\\bar\\baz'); // false
isRelative('foo/bar/baz.txt'); // true
isRelative('foo.md'); // true

const isHexColor = (color) => /^#([0-9A-F]{3}|[0-9A-F]{4}|[0-9A-F]{6}|[0-9A-F]{8})$/i.test(color);

isHexColor('#012'); // true
isHexColor('#A1B2C3'); // true
isHexColor('012'); // false
isHexColor('#GHIJKL'); // false

const diffDays = (date, otherDate) => Math.ceil(Math.abs(date - otherDate) / (1000 * 60 * 60 * 24));

diffDays(new Date('2014-12-19'), new Date('2020-01-01')); // 1839

const copyToClipboard = (text) => navigator.clipboard.writeText(text);

copyToClipboard("Hello World");