eslint-config-problems

eslint-config-problems

eslint-config-problems is an ESLint config that doesn't regulate your code style. It only catches actual problems with your code.

It's designed for use with Prettier, the opinionated code formatter; but you could also use this as a solid base config to add stylistic rules on top of.

Contents

• Rules
  • ES2015+
  • I disagree with rule X; you missed rule Y
• Installation & Usage
  • Just ESLint
  • With eslint-plugin-prettier
• License

Rules

Rules were chosen based on the following criteria:

• No stylistic rules; nothing that Prettier can fix
• Prevent guaranteed runtime errors (i.e. no undefined variables)
• Disallow "evil" things like eval
• Disallow archaic language features like with
• Disallow obvious bad practices like new Number(13)
• Point out places the code could be made shorter. For example:

  if (someCondition) return someValue;
  else {
    // Do something else
  }
  

  The else block is unneeded, since the if block contains a return statement. eslint-config-problems will point this out to you (or auto-fix with the --fix option).

ES2015+

By default eslint-config-problems forces the use of ES2015+ features supported by Node.js versions 10 and higher. Here are the rules enforced:

• no-var - Use let/const instead.
• object-shorthand - Use object shorthand where possible.
• prefer-arrow-callback - Use arrow functions as callbacks where possible.
• prefer-numeric-literals - Don't use parseInt() to write binary, octal, and hexadecimal numbers, use the literal form instead.
• prefer-template - Use template strings instead of string concatenation.
• prefer-spread - Use the spread operator instead of .apply where possible.
• prefer-rest-params - Use rest parameters instead of arguments.
• Use the exponentiation operator (**) instead of Math.pow() (enforced via no-restricted-properties).
• prefer-object-spread - Use object spread where possible, instead of Object.assign()
• Use optional catch bindings when not using the error variable in the catch block (enforced by no-unused-vars with caughtErrors: 'all')
• prefer-const - I realize this is very opinionated; if you don't like it, add prefer-const: off to your config.

It also sets ecmaVersion: 2020 in the parserOptions, so that ESLint can parse modern code (including BigInt in Node 10.8+) with no additional setup.

I disagree with rule X; you missed rule Y

If you disagree; feel free to open an issue. I'm open to changing rules if you have a good reason.

If I missed a rule that prevents an actual problem or is otherwise in keeping with the general guidelines above, please open an issue as well; I just might add it.

Installation & Usage

eslint-config-problems doesn't set any environments by default, other than the es6 environment. So you'll have to manually set your environment in your ESLint config. Here's a list of environments.

If you're using ES Modules, you will need to set sourceType: module in the parserOptions, like this:

parserOptions:
  sourceType: module

Just ESLint

npm install -D eslint eslint-config-problems

In your eslintrc.yaml:

extends: 'problems'
env:
  # Set your environments here; for example:
  node: true

With eslint-plugin-prettier

npm install -D eslint prettier eslint-config-problems eslint-plugin-prettier

In your eslintrc.yaml:

extends: 'problems'
env:
  # Set your environments here; for example:
  node: true
plugins:
  - prettier
rules:
  - prettier/prettier: error

License

ISC