require-no-implicit-override

Require "noImplicitOverride": true in compilerOptions to prevent subclasses from accidentally overriding base-class methods without the override keyword.

Targeted pattern scope

The compilerOptions.noImplicitOverride field in any tsconfig*.json file.

What this rule reports

This rule reports when compilerOptions is present and noImplicitOverride is absent or set to false. The rule does not report if compilerOptions is not defined at all.

Why this rule exists

Without noImplicitOverride, a subclass method silently shadows a base-class method of the same name. This makes it easy to accidentally override a method when the developer intended to add a new one, or to continue calling a method as "overriding" after the base class renames it.

With noImplicitOverride: true, TypeScript requires the override keyword on any method that shadows a base-class method, and reports an error if override is used on a method that does not exist in the base class.

This creates an explicit contract: all intentional overrides are marked, and accidental name collisions surface as compiler errors.

The auto-fixer adds "noImplicitOverride": true to compilerOptions.

❌ Incorrect

{
    "compilerOptions": {
        "strict": true
    }
}

noImplicitOverride is not part of strict and must be set explicitly.

✅ Correct

{
    "compilerOptions": {
        "strict": true,
        "noImplicitOverride": true
    }
}

When not to use it

Disable this rule for codebases with a large number of class hierarchies that have not yet adopted the override keyword and where the migration effort is not currently planned.

Package documentation

Rule catalog ID: R020

Targeted pattern scope​

What this rule reports​

Why this rule exists​

❌ Incorrect​

✅ Correct​

When not to use it​

Package documentation​

Further reading​