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.
H. Grosskreutz, S. Rüping, and S. Wrobel. ECML PKDD '08: Proceedings of the 2008 European Conference on Machine Learning and Knowledge Discovery in Databases - Part I, page 440--456. Berlin, Heidelberg, Springer-Verlag, (2008)
J. Tang, S. Chang, C. Aggarwal, and H. Liu. Proceedings of the Eighth ACM International Conference on Web Search and Data Mining, page 87--96. New York, NY, USA, ACM, (2015)
J. Li, P. Ren, Z. Chen, Z. Ren, and J. Ma. Proceedings of the 2017 ACM Conference on Information and Knowledge Management, page 1419--1428. New York, NY, USA, ACM Press, (2017)
M. McCord, and M. Chuah. Proceedings of the 8th International Conference on Autonomic and Trusted Computing, page 175--186. Berlin, Heidelberg, Springer-Verlag, (2011)
S. Doerfel, D. Zoller, P. Singer, T. Niebler, A. Hotho, and M. Strohmaier. Proceedings of the 16th LWA Workshops: KDML, IR and FGWM, Aachen, Germany, September 8-10, 2014., volume 1226 of CEUR Workshop Proceedings, page 18--19. CEUR-WS.org, (2014)
L. Bing, R. Guo, W. Lam, Z. Niu, and H. Wang. Proceedings of the 37th International ACM SIGIR Conference on Research &\#38; Development in Information Retrieval, page 767--776. New York, NY, USA, ACM, (2014)