close
Rslint

    new-cap

    Unreleased

    Configuration

    rslint.config.ts
    import { defineConfig, js } from '@rslint/core';

export default defineConfig([
  js.configs.recommended,
  {
    rules: {
      'new-cap': 'error',
    },
  },
]);

    Rule Details

    This rule requires constructor names to begin with an uppercase letter and requires functions whose names begin with an uppercase letter to be called with new.

    Examples of incorrect code for this rule:

    const friend = new person();
const colleague = Person();

    Examples of correct code for this rule:

    const friend = new Person();
const value = Boolean(input);

    The object option supports newIsCap, capIsNew, newIsCapExceptions, newIsCapExceptionPattern, capIsNewExceptions, capIsNewExceptionPattern, and properties. The two checks and property checking are enabled by default.

    {
  "new-cap": [
    "error",
    {
      "newIsCapExceptions": ["events"],
      "capIsNewExceptionPattern": "\\.Factory$",
      "properties": false
    }
  ]
}
    const emitter = new events();
const value = library.Factory();
const widget = new library.widget();

    Differences from ESLint

    ESLint's exception lookup also accepts names inherited from Object.prototype, such as constructor and toString, because its exception map is a plain JavaScript object. This is an upstream implementation accident. rslint uses an explicit string set, so lowercase constructor names are reported unless they are configured in newIsCapExceptions.

    Original Documentation