Skip to main content

no-non-null-asserted-nullish-coalescing

Disallow non-null assertions in the left operand of a nullish coalescing operator.

🔒

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

💡

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

The ?? nullish coalescing runtime operator allows providing a default value when dealing with null or undefined. Using a ! non-null assertion type operator in the left operand of a nullish coalescing operator is redundant, and likely a sign of programmer error or confusion over the two operators.

.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/no-non-null-asserted-nullish-coalescing": "error"
  }
};
Try this rule in the playground ↗

Examples​

foo! ?? bar;
foo.bazz! ?? bar;
foo!.bazz! ?? bar;
foo()! ?? bar;

let x!: string;
x! ?? '';

let x: string;
x = foo();
x! ?? '';
Open in Playground

Further Reading​

Options​

This rule is not configurable.

Resources​