There are quite a lot of similarities of es6 features from coffescript.
Based on what i researched and compared , i would conclude that Es6 borrowed alot from coffescript or es6 is influenced by some features in powerful backend programming languages like java. Nonetheless, coffescript implementation was released earlier based on its versioning information.

You can find the table below showing the similarities of features . To understand that partiicular feature, feel free to visit the official es6 site or google !