Copy text to the clipboard shouldn't be hard. It shouldn't require dozens of steps to configure or hundreds of KBs to load. But most of all, it shouldn't depend on Flash or any bloated framework. That's why clipboard.js exists.
A. Bellogin, P. Castells, and I. Cantador. Proceedings of the fifth ACM conference on Recommender systems - RecSys 2011, page 333 -- 336. ACM Press, (2011)
R. Cañamares, and P. Castells. Proceedings of the 40th International ACM SIGIR Conference on Research and Development in Information Retrieval, ACM, (August 2017)
X. He, L. Liao, H. Zhang, L. Nie, X. Hu, and T. Chua. Proceedings of the 26th International Conference on World Wide Web, page 173–182. Republic and Canton of Geneva, CHE, International World Wide Web Conferences Steering Committee, (2017)
A. Zimdars, D. Chickering, and C. Meek. UAI '01: Proceedings of the 17th Conference in Uncertainty in Artificial Intelligence, page 580--588. San Francisco, CA, USA, Morgan Kaufmann Publishers Inc., (2001)