An Optioned Guide to ESLint

eslint is a powerful and versatile tool. I myself only use eslint for problems coming from JavaScript design. Thus I can have a short rule list:

No Formatting Rule #

Use prettier instead.

I use prettier with its default options, without any configuration.

TypeScript Can Detect Lots of Errors #

ts-check can detect a lot of problems, and it is usually faster.

For example, the array-callback-return rule is unnecessary, because if I accidentally forget to write return statement in array mapping function, it tends to trigger a type error.

TypeScript also has other helpful checks like noFallthroughCasesInSwitch.

  "compilerOptions": {
    "strict": true,
    "noUnusedParameters": true,
    "noUnusedLocals": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true
    // more options omitted

Only Include Obvious Rules #

Do not include rules such as no-new-object and no-nested-ternary, which are merely personal choice of programming style.

So here is the seven ESLint rules I use:

"rules": {
    "eqeqeq": "error", // prefer `===` instead of `==`
    "prefer-arrow-callback": "error", // avoid the evil `this`
    "curly": "error", // not omit braces for statements in control flow
    "no-multi-assign": "error", // no `a = b = c = 1`
    "no-var": "error", // use `const` and `let` instead of `var`
    "prefer-const": "error", // use `const` when there is no reassignment
    "no-param-reassign": "error", // use nonreassignable function parameters

See an example of a full eslint configuration file.