update to Style and Testing guides (#727)

Author: cgorringe

STYLE_GUIDE.md

@@ -16,12 +16,13 @@ This is a style guide for the Web Extension code. Some of the code may not curre
  - Use double `(")` over single `(')` quotes for HTML attributes.
  - Use single `(')` over double `(")` quotes for CSS property values.
  - Inlined styles in HTML is OK temporarily, but please try to move to the .css file before final submission.
+ - If you're repeating the same styles on multiple *#ids*, consider placing those styles in a class!
 
 #### Naming ####
 
  - CSS ids and classes should be in `hyphen-style`. 
  - Try to avoid using CamelCase or underscores.
-
+ - Try to limit use of single-word classes and ids. 2-word ids are better. 3-word ids are fine too.
 
 #### Example ####
 
@@ -51,7 +52,7 @@ This is a style guide for the Web Extension code. Some of the code may not curre
  - Function names should be in `lowerCamelCase`.
  - Class names in `UpperCamelCase`.
  - Variables can be `lowercase`, `lowerCamelCase`, or `under_scored`.
- - Global or class-scoped constants in `CONSTANT_CASE`. Locally-scoped may remain lowercased if desired.
+ - Global or class-scoped constants in `CONSTANT_CASE`. Since `const` in Javascript doesn't really mean constant, but *one-time assignment*, please only convert *true* constants to uppercase (e.g. `const PI = 3.14159`), and leave the rest like variable names.
 
 #### Example ####
 

TESTING_GUIDE.md

@@ -16,19 +16,21 @@ After modifying code, run **eslint** to catch basic formatting and syntax issues
 
 #### To Install ####
 
-```
-npm install eslint --save-dev
-```
+If you haven't already set up your testing environment, run `npm install` to install the required packages including `eslint` which is  listed in `package.json`.
 
 #### Running ESLint ####
 
-Run from the root directory where `package.json` is located:
+Run from the root directory where `package.json` is located.
 
-```
-npx eslint webextension/scripts/example.js
-OR
-eslint webextension/scripts/example.js
-```
+##### To see options: #####
+
+`npx eslint`
+
+This runs the version of eslint located at `node_modules/.bin/`. Some people install eslint globally on their system. If that is your case you may leave out the `npx` part if you want.
+
+##### To lint a js file: #####
+
+`npx eslint webextension/scripts/example.js`
 
 - Recommend **not** using the `--fix` option but first try to fix it manually.