no-non-null-assertion

Disallows non-null assertions using the ! postfix operator.

Attributes

• Included in configs
  • ✅ Recommended
  • 🔒 Strict
• Fixable
  • 🔧 Automated Fixer
  • 🛠 Suggestion Fixer
• 💭 Requires type information

Rule Details

Using non-null assertions cancels the benefits of the strict null-checking mode.

Examples of code for this rule:

❌ Incorrect

interface Foo {
  bar?: string;
}

const foo: Foo = getFoo();
const includesBaz: boolean = foo.bar!.includes('baz');

✅ Correct

interface Foo {
  bar?: string;
}

const foo: Foo = getFoo();
const includesBaz: boolean = foo.bar?.includes('baz') ?? false;

Options

// .eslintrc.json
{
  "rules": {
    "@typescript-eslint/no-non-null-assertion": "warn"
  }
}

This rule is not configurable.

When Not To Use It

If you don't care about strict null-checking, then you will not need this rule.