Tuesday, July 3, 2018
NodeJS – Linting
NodeJS – Linting
Process of checking source code for programmatic as well as stylistic errors is called linting. These tools provide us the code analysis. They don�t run the code but inspect it by looking for typos or anti-patterns
Bug detection and maintainability are some of the uses we obtain by using the linting tools.
Eslint � Eslint is an Open Source Project whose goal is to provide a pluggable linting utility for Java Script. ESLint is a tool that analyses your code and points out any issues it finds. It can find bugs, potential problem areas, poor coding styles and stylistic issues. Best of all it�s highly configurable. Eslint is chosen to be a linting tool for Nodejs applications in Cloud automation.
Some of the noticeable points about Eslint are
� ECMAScript is a Standard for scripting languages. Languages like JavaScript are based on the ECMAScript standard.
� ESLint is a tool for identifying and reporting on patterns found in ECMAScript/JavaScript code, with the goal of making code more consistent and avoiding bugs.
� Easily Pluggable and Extensible.
� Written in JavaScript on Node.js
� Supports custom reporters
� Supports ES6 ( new ECMAScript Standards )
� All rules are plugins, more can be added at runtime.
� Different parsers can be used (Esprima, Espree or Babel are currently compatible).
� Integrates with editors, build systems, command line tools, and more!
Installation �
Eslint can be installed either locally or globally.
Install Eslint locally as,
Install eslinnt : npm install eslint --save-dev
setup a configuration file : ./node_modules/.bin/eslint --init
Run ESLint on Source code as : ./node_modules/.bin/eslint yourfile.js
Install Eslint globally as
Install eslint : npm install -g eslint
Setup a configuration file : eslint �init
Run ESLint on any file or directory : eslint yourfile.js
Note - eslint --init is intended for setting up and configuring ESlint on a per-project basis and will perform a local installation of ESlint and its plugins in the directory in which it is run. If you prefer using a global installation of ESlint, any plugins used in your configuration must also be installed globally.
Eslint getting Started �
To get started with the Eslint tool, first create a configuration file using
/node_modules/.bin/eslint --init
This will present with options
- You will be asked a few questions about your coding style, and the generated config file will be based on your answers
- community-developed style guides available as shared ESlint configs which can be installed and used
- It will result in the most strict configuration (enabling the most rules)
Follow the below steps to get started with Eslint
Once the configuration file is created , run the test on sample code below
function test() {
var myVar = Hello, World;
console.log(myvar);
}
We will be given with the Eslint response as below
We can obtain configuration file that are sharable at this moment. We have chosen to use �google� configuration file and made tweaks to the rules according to the project.
