#no-use-before-define

#Configuration

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

export default defineConfig([
  ts.configs.recommended,
  {
    rules: {
      '@typescript-eslint/no-use-before-define': 'error',
    },
  },
]);

#Rule Details

Disallow the use of variables before they are defined.

This rule extends the base ESLint no-use-before-define rule to add support for TypeScript-specific constructs like type, interface, and enum declarations.

Examples of incorrect code for this rule:

alert(a);
var a = 10;

f();
function f() {}

new A();
class A {}

const foo = Foo.FOO;
enum Foo { FOO }

Examples of correct code for this rule:

var a = 10;
alert(a);

type Foo = string;
const x: Foo = "hello";

function f() {}
f();

#Options

• functions (boolean, default true) - Whether to check function declarations
• classes (boolean, default true) - Whether to check class declarations
• variables (boolean, default true) - Whether to check variable declarations
• enums (boolean, default true) - Whether to check enum declarations
• typedefs (boolean, default true) - Whether to check type/interface declarations and type parameters
• ignoreTypeReferences (boolean, default true) - Whether to ignore references in type annotations
• allowNamedExports (boolean, default false) - Whether to allow references in named exports

Also accepts "nofunc" as a shorthand for { functions: false }.

With allowNamedExports: true, named exports follow the other options. The default ignoreTypeReferences: true ignores them, but setting it to false checks them according to the referenced declaration. For example, export { value }; const value = 1; is reported with { allowNamedExports: true, ignoreTypeReferences: false }.

#Original Documentation

• typescript-eslint: no-use-before-define
• Source code