gulp plugin for .env files

gulp-plugin.js

const through = require("through2")

function changeEnvToDev(val) {
  return through.obj(function(file, encoding, callback) {
    if (file.isNull()) return callback(null, file)

    if (file.isStream()) {
      //file.contents = file.contents.pipe(...
      //return callback(null, file);
      this.emit("error", new Error("Streams not supported!"))
    } else if (file.isBuffer()) {
      let fc = file.contents.toString().split("\n")
      fc[fc.findIndex(f => f.startsWith("NODE_ENV"))] = `NODE_ENV=${val}`
      file.contents = new Buffer(String(fc.join("\n")))
      return callback(null, file)
    }
  })
}