Issue #1474 - added documentation

docs/pr-coding-guidelines.md

@@ -19,34 +19,34 @@ All code contributions should come in the form of a pull request, as a topic bra
 
     ```bash
     # makes sure, you are on the master branch
-    git checkout master 
-    
+    git checkout master
+
     # if you are SURE your fork is up-to-date
     git pull origin master
-    
-    # OR 
+
+    # OR
     # if you are NOT SURE your fork is up-to-date
     git pull upstream master  
-    
+
     # creates new branch
     git checkout -b issues/NumberOfIssue/VersionOfPR  
     ```
 
 5. Create your patch; commit your changes. Referencing the issue number you're working on from the message is recommended.
 
     > Note: Please keep the title under 50 chars. If you'd like to provide more information, just add the details to the commit body.
-    
+
     ```bash
     # check for changed files
     git status
-    
+
     # add files to commit, e.g. as following
-    git add file.js foldername/foldername2/file2.js 
-    
+    git add file.js foldername/foldername2/file2.js
+
     # add commit message including issue number
     git commit -m 'Issue #NumberOfIssue - Fixes broken layout on mobile browsers'    
     ```
-    
+
 6. Push your branch to GitHub:
 
     `git push origin issues/NumberOfIssue/VersionOfPR`
@@ -144,10 +144,18 @@ We do not use frameworks. However we use libraries, such suitcss-components-grid
 
 ### Javascript
 
-The js folder contains two subfolders: `lib` contains all project source files and `vendor` contains all third party libraries. The files out of the two sub folders contain the compiled source code.
+The js folder contains two sub folders: `lib` contains all project source files and `vendor` contains all third party libraries. The files out of the two sub folders contain the compiled source code.
 
 > Note: All code changes should be made to the files in `lib`
 
+#### Linting
+
+For the consistency of our codebase, we use eslint with these rules: https://github.com/webcompat/webcompat.com/blob/master/.eslintrc. We also use Prettier for formatting our code. We have set up two recipes to check and fixe the codebase.
+
+`npm run lint` check all JavaScript files and display the resulting errors. If you get errors, you have two possibilities. You can correct yourself or you can run `npm run fix` which use Prettier to format the code. 
+
+In order to avoid errors during a Pull Request, `npm run lint` will be executed before each commit.
+
 @@something to write by miketaylr@@