Возможно, вы ищете merge-dirs
Использование:
var mergedirs = require('merge-dirs');
// copy folder/a into folder/b
mergedirs('/folder/a', '/folder/b');
// copy folder/a into folder/b with conflict resolution 'overwrite'
mergedirs('/folder/a', '/folder/b', 'overwrite');
// copy folder/a into folder/b with conflict resolution 'ask'
mergedirs('/folder/a', '/folder/b', 'ask');
// copy folder/a into folder/b with conflict resolution 'skip'
mergedirs('/folder/a', '/folder/b', 'skip');