Rules

WARNING: Before configuring any of the following rules, you should ensure that TSLint’s no-unused-variable rule is not enabled in your configuration (or in any configuration that you extend). That rule has caused problems in the past - as it leaves the TypeScript program in an unstable state - and has a significant number of still-open issues. Consider using this package’s no-unused-declaration rule instead.

The package includes the following rules (none of which are enabled by default):

Rule Description Fixer Options
ban-imports Disallows the use of banned imports. No See below
no-assign-mutated-array Disallows the assignment of returned, mutated arrays. Useful for those times you forget that sort and reverse mutate the array upon which they are called. No None
no-const-enum Disallows the use of const enum. Constant enums are not compatible with isolated modules. No See below
no-enum Disallows the use of enum. No None
no-missing-dollar-expect Disallows dtslint $ExpectType and $ExpectError expectations if the $ is missing. No None
no-unsafe-callback-scope Disallows the use of variables/properties from unsafe/outer scopes in callbacks. No None
no-unused-declaration Disallows unused declarations. Yes, but see below See below
throw-error Enforces the use of Error values when throwing or rejecting. No None

Options

ban-imports

The ban-imports rule takes an object containing keys that are regular expressions and values that are either booleans or strings containing the explanation for the ban.

For example, to following configuration would disallow "foo" with an explanation, would disallow "bar" without an explanation and would allow "baz":

"rules": {
  "ban-imports": {
    "options": [{
      "^foo$": "'foo' has been deprecated; use 'baz'",
      "^bar$": true,
      "^baz$": false
    }],
    "severity": "error"
  }
}

no-const-enum

This rule takes an optional object with an optional allowLocal property - which defaults to false. If allowLocal is true, only exported const enums are forbidden.

For example, to following configuration would local (i.e. non-exported) const enums:

"rules": {
  "no-const-enum": {
    "options": [{
      "allowLocal": true
    }],
    "severity": "error"
  }
}

no-unused-declaration

This rule has a fixer. However, the fixer will only remove unused import declarations. It will not remove other kinds of declarations, as doing so could be potentially destructive.

For example, having it remove a function that you’ve spent time writing - just because you’ve not yet exported or called it - would be too dispiriting, so the rule will just flag it as a failure and leave the function untouched.

The rule takes an optional object with optional imports and declarations properties. The properties are booleans and determine whether or unused imports or declarations are allowed. The properties default to true.

For example:

"rules": {
  "no-unused-declaration": {
    "options": [{
      "declarations": true,
      "imports": true
    }],
    "severity": "error"
  }
}