const regex = new RegExp('^(?P<artist>.+?(?=\\s-\\s)) # artist with pos. lookahead
\\s-\\s # space - space
(?P<title>.+?(?=(?:\\(?Feat\\.)|$)) # title with pos. lookahead
\\(? # optional open parenthesis
(?P<artist2>Feat\\.[^()\\n]+)? # artist2 with Feat. before
\\)? # optional closing parenthesis
(?P<subtitle>.+)?$ # optional subtitle', 'gm')
const str = `Black Coast - Trndsttr
Black Coast - Trndsttr (Feather)
Black Coast - Trndsttr (Lucian Remix)
Black Coast - Trndsttr (Feather) (Lucian Remix)
Black Coast - Trndsttr Feat. M. Maggie
Black Coast - Trndsttr (Feat. M. Maggie)
Black Coast - Trndsttr Feat. M. Maggie (Lucian Remix)
Black Coast - Trndsttr (Feat. M. Maggie) (Lucian Remix)
Black Coast - Trndsttr (Lucian Remix) Feat. M. Maggie
Black Coast - Trndsttr (Lucian Remix) (Feat. M. Maggie)
Black Coast - Trndsttr (Feather) (Lucian Remix) Feat. M. Maggie
Black Coast - Trndsttr (Feather) (Lucian Remix) (Feat. M. Maggie)
Black Coast - Trndsttr (Feather) Feat. M. Maggie (Lucian Remix)
Black Coast - Trndsttr (Feather) (Feat. M. Maggie) (Lucian Remix)
Black Coast - Trndsttr (Feather) (Feat. M. Maggie) Lucian Remix
Black Coast - Trndsttr (Feather) Feat. M. Maggie Lucian Remix
`;
const subst = `$1 $3 - $2$4`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions