> How did you do one file at a time? I suspect they just flipped a switch causing all files to be run through the transpiler, regardless of filename extension

> How did you do one file at a time? I suspect they just flipped a switch causing all files to be run through the transpiler, regardless of filename extension or anything. However at the time the switch was flipped, none of those files actually contained any ES6-specific syntax, so the transpiler was mainly just passing code through unchanged, even though it technically is transpiling everything. Now they're simply going through the code and swapping in ES6 syntax here and there. It all works because 6 is a superset of 5.