gulpfile.js

var gulp = require('gulp');
var browserSync = require('browser-sync');
var runSequence = require('run-sequence');
var ts = require('gulp-typescript');
var merge = require('merge2');
var less = require('gulp-less');
var path = require('path');
var cache = require('gulp-cached');
var requirejsOptimize = require('gulp-requirejs-optimize');
var rename = require('gulp-rename');

gulp.task('build-less', function () {
  return gulp.src('app/**/*.less')
    .pipe(cache('less'))
    .pipe(less())
    .pipe(gulp.dest('app'));
});

// gulp.task('build-bundle', ['build-less', 'build-ts'], function() {
//   return gulp.src('src/app.js')
//     .pipe(requirejsOptimize({
//       optimize: 'none',
//       name: 'pp-manifest',
//       excludeShallow: ['text'],
//       paths: {
//         "aurelia-framework": "empty:",
//         "aurelia-fetch-client": "empty:",
//         "aurelia-router": "empty:",
//         "pplatform": "../src",
//         "text": "../node_modules/text/text"
//       }
//     }))
//     .pipe(rename("plotter-platform-bundle.js"))
//     .pipe(gulp.dest('scripts'));
// });

var tsProject = ts.createProject({
      typescript: require('typescript'),
      declaration: true,
      noExternalResolve: true,
      target: "es5",
      module: "amd",
      emitDecoratorMetadata: true,
      "experimentalDecorators": true
    });

gulp.task('build-ts', function () {
  var tsResult = gulp.src(myPaths.ts,
    { base: "./" })
    .pipe(cache('ts'))
    .pipe(ts(tsProject));

  return merge([
    tsResult.dts.pipe(gulp.dest('./plotterplatformtypings/')),
    tsResult.js.pipe(gulp.dest('./'))
  ]);
});

gulp.task('build', ['build-less', 'build-ts']);

var myPaths = {
  ts: ['app/**/*.ts', 'views/**/*.ts', 'typings/**/*.d.ts'],
  js: "app/**/*.js",
  html: "app/**/*.html",
  css: "app/**/*.css",
  less: "app/**/*.less"
}

gulp.task('serve', ['build'], function (done) {
  browserSync({
    open: false,
    port: 9000,
    server: {
      baseDir: ['.'],
      middleware: function (req, res, next) {
        res.setHeader('Access-Control-Allow-Origin', '*');
        next();
      }
    }
  }, done);
});

function reportChange(event) {
  console.log('File ' + event.path + ' was ' + event.type + ', running tasks...');
}

gulp.task('watch', ['serve'], function () {
  gulp.watch(myPaths.ts, ['build-ts']).on('change', reportChange);
  gulp.watch(myPaths.less, ['build-less']).on('change', reportChange);
  gulp.watch(myPaths.js, [browserSync.reload]).on('change', reportChange);
  gulp.watch(myPaths.html, [browserSync.reload]).on('change', reportChange);
  gulp.watch(myPaths.css, [browserSync.reload]).on('change', reportChange);
});