Automate Angular Js / Javascript code analysis with EsLint and Gulp Js in Visual Studio

Krishna KV
 
Team Leader, Aspire Systems
March 5, 2016
 
Rate this article
 
Views
16361

EsLint helps us to avoid silly mistakes that happens in a JavaScript program. For example, it is always hard to find a missing variable or function in a medium or large JavaScript application. EsLint will helps us to analyze the code and find the bugs and ensures proper coding styles guidelines is followed across the application.

EsLint is a JavaScript linting that builds in the top of Esprima. It can be used to check the JavaScript error & Styles. It is more flexible and highly configurable. The primary goal is that developers can write their own rules, but still we have the default rules which we can be changed or extended.

  • ES6 Support
  • Support for Angular JS
  • Custom Reporter
  • Validate JSX
  • More Plugins
  • Style checker
  • Rules are Pluggable
  • Customized error or warning

Validation

  • Syntax errors
  • Coding standard
  • Missing or unnecessary semicolons
  • Unreachable code
  • Unused parameters
  • Missing closing brackets
  • It is used to enforce a set of style and consistency rule.
  • Check for variable names
  • Coding Standard

Package.Json

 {
   "name": "jsvalidator",
   "version": "1.0.0",
   "description": "Javascript validation test",
   "devDependencies": {
     "gulp": "3.9.1",
     "gulp-eslint": "2.0.0",
     "gulp-jshint": "2.0.0",
     "jshint": "2.9.1",
     "jshint-stylish": "2.1.0",
     "eslint-plugin-angular": "1.0.0"
   } 
 }

gulpfile.js

 var gulp = require('gulp');
 var eslint = require('gulp-eslint');
 var stylish = require('jshint-stylish');
 var angularPlugin = require('eslint-plugin-angular');
 var config =
     {
         apps: ['app/**/*.js'],
         html: ['*.html', 'app/**/*.html']
     };
 
 
 gulp.task('validateSyntax-eslint', [], function () {
     return gulp.src(config.apps)
     .pipe(eslint())
     .pipe(eslint.format())
 });

Task Runner

We can view the list of task available in the gulp. Run the task validateSyntax-eslint. As we have not added or not configured the rules, it won’t display any errors/warning.

clip_image002

Let’s add the EsLint default rule.

 gulp.task('validateSyntax-eslint', [], function () {
     return gulp.src(config.apps)
     .pipe(eslint(
         {"extends": ["eslint:recommended"]   
         }))
     .pipe(eslint.format())
 });

clip_image004

Customizing the errors.

 gulp.task('validateSyntax-eslint', [], function () {
     return gulp.src(config.apps)
     .pipe(eslint(
         {
             "extends": ["eslint:recommended"],
             "plugins": ["angular"], 
             "env": {
                 "browser": true
             },
 
             "globals": {
                 'jQuery': true,
                 '$': true,
                 "angular": true,
                 "app":true
             },
             'rules': {
                 'quotes': [0, 'single'],
                 'semi': [2, 'always'],
                 'no-unused-vars': 1,
                 'no-console': 0,            
             }
         }))
     .pipe(eslint.format())
 });

More rules can be found here : https://github.com/eslint/eslint/blob/master/conf/eslint.json

clip_image005

The unused variables are shown as a warning due the configuration ‘no-unused-vars’: 1, Changing the value to 2 will be shown as error

0- Disabled

1- Warning

2- Error

clip_image006

Adding Angular Js Validation

· Controller name should be starts with [A-Z] followed by Controller.

· Directive & Filter should be added prefix with dir and flr

· Disallow empty controller

Include the required plugin in gulp.js and package.json – ‘eslint-plugin-angular’

 var gulp = require('gulp');
 var eslint = require('gulp-eslint');
 var stylish = require('jshint-stylish');
 var angularPlugin = require('eslint-plugin-angular');
 var config =
     {
         apps: ['app/**/*.js'],
         html: ['*.html', 'app/**/*.html']
     };
 
 
 gulp.task('validateSyntax-eslint', [], function () {
     return gulp.src(config.apps)
     .pipe(eslint(
         {
             "extends": ["eslint:recommended"],
             "plugins": ["angular"],
             "env": {
                 "browser": true
             },
 
             "globals": {
                 'jQuery': true,
                 '$': true,
                 "angular": true,
                 "app":true
             },
             'rules': {
                 'quotes': [0, 'single'],
                 'semi': [0, 'always'],
                 'no-unused-vars': 0,
                 'no-console': 0,              
                 "angular/controller-name": [1, "/[A-Z].*Controller$/"],
                 "angular/directive-name": [2, "cus"],
                 "angular/empty-controller": 2,
                 "angular/filter-name": [2,"flr"]
                 
 
 
             }
         }))
     .pipe(eslint.format())
 });

More rules can be found here : https://www.npmjs.com/package/eslint-plugin-angular

clip_image008

Author Info

Krishna KV
 
Team Leader, Aspire Systems
 
Rate this article
 
Krishna K.V has been working in IT Industry for over 7+ years. He holds a Master Degree in Information Technology. He is more interested to learn and share new technologies, ...read more
 

Leave a comment