Via @blackgate:
Sure:
const fs = require("fs");
const browserify = require("browserify");
browserify("./script.js", { debug: true })
.transform("babelify", {presets: ["env"], sourceMaps: true})
.transform("brfs")
.bundle()
.pipe(fs.createWriteStream("bundle.js"));
With the .transform("brfs") line, the sourcemap contains the transpiled source instead of the original.
Via @blackgate: