ESLint Integration with VS Code
Learn how to integrate and configure ESLint in VS Code.
Extending an ESLint configuration
Following are the steps to extend an ESLint configuration:
-
ESLint is now perfectly suited for
palindromes.js
, but if you try to run it againstpalindromes.test.js
, it won’t go well:$ npx eslint palindromes.test.js /Users/tburnham/code/test-driven-palindromes/palindromes.test.js 3:1 error 'describe' is not defined no-undef 4:3 error 'it' is not defined no-undef 5:5 error 'expect' is not defined no-undef ✖ 3 problems (3 errors, 0 warnings)
All of these problems share the same cause as the
module
kerfuffle earlier: ESLint doesn’t know thatpalindromes.test.js
will be running in an environment (Jest) wheredescribe
,it
, andexpect
are defined as globals. -
You could fix the problem with another
env
entry, but there’s a better way. Jest has an official ESLint plugin, eslint-plugin-jest, which comes with several rules for identifying common test code mistakes. Go ahead and add it to the project:$ npm install --save-dev eslint-plugin-jest@22.1.2 + eslint-plugin-jest@22.1.2
-
To apply the plugin, you need to make two ...
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