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typescript/require-prop-type-annotation

Require type annotations for class properties without initializers.

Targeted pattern scope​

This rule targets class PropertyDefinition nodes where both are true:

  • typeAnnotation is missing, and
  • value is null (no initializer).

What this rule reports​

This rule reports class properties that have no initializer and no type annotation.

Why this rule exists​

Uninitialized properties without annotations leave property type intent unclear.

❌ Incorrect​

class C {
 value;
}

✅ Correct​

class C {
 value: string;
}

Behavior and migration notes​

This rule reports only and does not provide an autofix.

Migration is adding explicit property type annotations for uninitialized declarations.

Options​

This rule has no options.

Additional examples​

class User {
 name = "anonymous";
 // ✅ valid: initializer provides type

 role;
 // ❌ reported: no initializer and no annotation
}

ESLint flat config example​

import etcMisc from "eslint-plugin-etc-misc";

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/typescript/require-prop-type-annotation": "error",
  },
 },
];

When not to use it​

Disable this rule if implicit any-style property declarations are allowed.

Package documentation​

Rule catalog ID: R141

Further reading​

Adoption resources​

  • Start at warning level in CI, then move to error after cleanup.
  • Use focused codemods/autofix batches per package or directory.