fix(webpack): clean dist folder before build

au build --watch essentially does webpack --watch which doesn't clear the dist directory by itself, resulting in many files over time. This still happens, but it gets emptied before a new au build command is ran

lib/commands/new/buildsystems/webpack/index.js

@@ -56,6 +56,7 @@ module.exports = function(project, options) {
     'expose-loader',
     'style-loader',
     'url-loader',
+    'del',
     'css-loader',
     'nps-utils',
     'file-loader',

lib/dependencies.json

@@ -39,6 +39,7 @@
   "cross-env": "5.0.1",
   "css-loader": "0.28.4",
   "debounce": "^1.0.2",
+  "del": "^3.0.0",
   "event-stream": "^3.3.3",
   "expose-loader": "0.7.3",
   "extract-text-webpack-plugin": "3.0.0",

lib/resources/tasks/build-webpack.js

@@ -4,6 +4,7 @@ import project from '../aurelia.json';
 import {CLIOptions, Configuration} from 'aurelia-cli';
 import gulp from 'gulp';
 import configureEnvironment from './environment';
+import del from 'del';
 
 const buildOptions = new Configuration(project.build.options);
 const production = CLIOptions.getEnvironment() === 'prod';
@@ -35,7 +36,12 @@ function onBuild(err, stats) {
   }
 }
 
+function clearDist() {
+  return del([config.output.path]);
+}
+
 const build = gulp.series(
+  clearDist,
   configureEnvironment,
   buildWebpack
 );

lib/resources/tasks/build-webpack.ts

@@ -4,6 +4,7 @@ import * as project from '../aurelia.json';
 import {CLIOptions, Configuration} from 'aurelia-cli';
 import * as gulp from 'gulp';
 import configureEnvironment from './environment';
+import * as del from 'del';
 
 const buildOptions = new Configuration(project.build.options);
 const production = CLIOptions.getEnvironment() === 'prod';
@@ -35,7 +36,12 @@ function onBuild(err, stats) {
   }
 }
 
+function clearDist() {
+  return del([config.output.path]);
+}
+
 const build = gulp.series(
+  clearDist,
   configureEnvironment,
   buildWebpack
 );