The clean-js jake command helps remove all minified js files that get generated using the minify bundle jake command

By running clean-js before running the minify command, we ensure that the tinymce files are consistent after being rebuilt/minified.

This is helpful with multiple app servers that are applying the same changes to the TinyMCE editor

This ensures that no matter on which machine the files are rebuilt, the resulting minified plugin files are consistent among all