#no-redeclare

#Configuration

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

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

#Rule Details

This rule disallows redeclaring variables. It extends ESLint's base no-redeclare to understand TypeScript constructs such as type aliases, interfaces, namespaces, and declaration merging.

Examples of incorrect code for this rule:

var a = 3;
var a = 10;

function a() {}
function a() {}

type T = 1;
type T = 2;

Examples of correct code for this rule:

var a = 3;
var b = function () {
  var a = 10;
};

interface A {
  prop1: 1;
}
interface A {
  prop2: 2;
}

class Foo {}
namespace Foo {}

#Options

#builtinGlobals (default: true)

When true, the rule reports redeclaring ECMAScript built-in globals and names provided by TypeScript's active lib type definitions, such as Object, Promise, or HTMLElement. Configured languageOptions.globals also participate as built-ins; use the globals catalog exported by @rslint/core to select a runtime environment. Active /* global */ directives participate as declarations in either mode; a final :off setting removes that inline global. Turning off a value global does not remove a same-named TypeScript type global.

{ "@typescript-eslint/no-redeclare": ["error", { "builtinGlobals": true }] }

var Object = 0;

#ignoreDeclarationMerge (default: true)

When true, the rule ignores redeclarations that are legal TypeScript declaration merges:

• interface + interface
• namespace + namespace
• class + interface / class + namespace / class + interface + namespace (at most one class)
• function + namespace (at most one function)
• enum + namespace (at most one enum)

{ "@typescript-eslint/no-redeclare": ["error", { "ignoreDeclarationMerge": true }] }

function A() {}
namespace A {}

#Original Documentation

• typescript-eslint: no-redeclare
• Source code