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no-non-null-asserted-optional-chain

Disallow non-null assertions after an optional chain expression.

✅

Extending "plugin:@typescript-eslint/recommended" in an ESLint configuration enables this rule.

💡

Some problems reported by this rule are manually fixable by editor suggestions.

?. optional chain expressions provide undefined if an object is null or undefined. Using a ! non-null assertion to assert the result of an ?. optional chain expression is non-nullable is likely wrong.

Most of the time, either the object was not nullable and did not need the ?. for its property lookup, or the ! is incorrect and introducing a type safety hole.

eslint.config.mjs
export default tseslint.config({
  rules: {
    "@typescript-eslint/no-non-null-asserted-optional-chain": "error"
  }
});

Try this rule in the playground ↗

Examples​

foo?.bar!;
foo?.bar()!;
Open in Playground

Options​

This rule is not configurable.

When Not To Use It​

If your project's types don't yet fully describe whether certain values may be nullable, such as if you're transitioning to strictNullChecks, this rule might create many false reports. You might consider using ESLint disable comments for those specific situations instead of completely disabling this rule.

Further Reading​

Resources​