gulpfile.js

const babel = require("gulp-babel"),
  gulp = require("gulp"),
  insert = require("gulp-insert"),
  plumber = require("gulp-plumber"),
  rename = require("gulp-rename"),
  sourcemaps = require("gulp-sourcemaps"),
  through = require("through2"),
  uglify = require("gulp-uglify"),
  webpack = require("webpack-stream");
const pack = require("./package.json");

gulp.task("sub", () => {
  // Reason behind having sub as separate task:
  // https://github.com/shama/webpack-stream/issues/114
  return gulp
    .src("./DateTime.js")
    .pipe(webpack(getWebpackConfig()))
    .pipe(gulp.dest("tmp/"));
});

gulp.task(
  "build",
  gulp.series("sub", () => {
    return (
      gulp
        .src(["tmp/react-datetime.js"])
        .pipe(sourcemaps.init({ loadMaps: true }))
        .pipe(
          through.obj(function(file, enc, cb) {
            // Dont pipe through any source map files as
            // it will be handled by gulp-sourcemaps
            const isSourceMap = /\.map$/.test(file.path);
            if (!isSourceMap) this.push(file);
            cb();
          })
        )
        .pipe(plumber())
        // .pipe( babel( { presets: [ 'es2015'] } ) )
        .pipe(insert.prepend(setHeader))
        .pipe(gulp.dest("dist/")) // Save .js
        .pipe(uglify())
        .pipe(insert.prepend(setHeader))
        .pipe(rename({ extname: ".min.js" }))
        .pipe(sourcemaps.write("."))
        .pipe(gulp.dest("dist/"))
    ); // Save .min.js
    // TODO: Remove tmp folder
  })
);

gulp.task("default", gulp.series("build"));

/*
 * Utility functions
 */

const getWebpackConfig = () => {
  return {
    devtool: "#cheap-module-source-map",
    output: {
      library: "Datetime",
      libraryTarget: "umd",
      filename: "react-datetime.js"
    },
    module: {
      loaders: [
        {
          test: /\.json$/,
          loader: "json-loader"
        }
      ]
    }
  };
};

const setHeader = "/*\n%%name%% v%%version%%\n%%homepage%%\n%%license%%: https://github.com/YouCanBookMe/react-datetime/raw/master/LICENSE\n*/\n"
  .replace("%%name%%", pack.name)
  .replace("%%version%%", pack.version)
  .replace("%%license%%", pack.license)
  .replace("%%homepage%%", pack.homepage);