Add npm run watch script for file watching (#26)

docs/developer/install.md

@@ -77,6 +77,24 @@ example data) using Firefox Nightly, you can just run (without adding flags):
 npm run run
 ```
 
+## Running the extension with file watchers
+
+To **run the extension with reloading on file change**:
+
+```sh
+npm run watch
+```
+
+This command will run the extension in Firefox. Additionally, it will start
+watch processes that will do the following on any file change:
+
+* run JS and CSS linting
+* rebuild the extension
+* reload the extension in the browser
+
+Note that you will need to set `webext_runflags` to specify flags for running
+Firefox, as this command does not accept any options.
+
 ## Testing the extension
 
 There are two forms of autmomated testing present: unit (test individual classes as much in isolation to everything else -- including the browser internals) and integration.

package.json

@@ -28,9 +28,17 @@
     "run": "cross-env-shell web-ext run --source-dir ./dist ${npm_config_webext_runflags}",
     "pretest": "npm run autolint && npm run clean:coverage",
     "test": "cross-env NODE_ENV=test karma start --single-run",
+    "test:watch": "cross-env NODE_ENV=test karma start",
     "preintegration": "cross-env NODE_ENV=test npm run build",
     "integration": "cross-env NODE_ENV=test mocha --require @babel/register --timeout 10000 test/integration/**/*-test.js",
-    "codecov": "codecov"
+    "codecov": "codecov",
+    "prewatch": "npm run build",
+    "watch": "npm-run-all --parallel :watch:*",
+    ":watch:build": "webpack --watch",
+    ":watch:run": "cross-env-shell web-ext run --source-dir ./dist ${npm_config_webext_runflags}",
+    ":watch:lint": "npm-run-all --parallel :watch:lint:*",
+    ":watch:lint:js": "onchange -v \"src/**/*.js\" -- npm run :autolint:js",
+    ":watch:lint:css": "onchange -v \"{docs,src}/**/*.css\" -- npm run :autolint:css"
   },
   "author": "Lockbox Team <lockbox-dev@mozilla.com>",
   "license": "MPL-2.0",
@@ -72,6 +80,8 @@
     "karma-sourcemap-loader": "^0.3.7",
     "karma-webpack": "^3.0.5",
     "mocha": "^5.2.0",
+    "npm-run-all": "^4.1.5",
+    "onchange": "^5.2.0",
     "redux-mock-store": "^1.5.3",
     "sinon": "^6.3.5",
     "sinon-chai": "^3.2.0",