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 4 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-const - I realize this is very opinionated; if you don't like it, add prefer-const: off to your config.

If you would like a config that omits these rules, for use in ES5 environments, I'd be glad to add such a config. Just open an issue.

---

There is a sub-config, accessed via extends: problems/node6 that contains the base config, plus these additional rules:

• prefer-spread - Use the spread operator instead of .apply where possible.
• prefer-rest-params - Use rest parameters instead of arguments.

This is for use in Node versions 6 and higher that support rest/spread.

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 (to turn on the ES2015 parser, allow Promise, etc.) So you'll have to manually set your environment in your ESLint config. Here's a list of environments.

Just ESLint

npm install -D eslint eslint-config-problems

In your eslintrc.yaml:

extends: 'problems' # or extends: 'problems/node6'
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' # or extends: 'problems/node6'
env:
  # Set your environments here; for example:
  node: true
plugins:
  - prettier
rules:
  - prettier/prettier: error

License

ISC