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throw-new-error

Require new when throwing error instances.

Targeted pattern scope​

This rule targets thrown error-constructor call expressions.

What this rule reports​

This rule reports throw Error(...) and related patterns without new.

Why this rule exists​

throw new Error(...) is explicit and consistent with constructor semantics.

❌ Incorrect​

throw Error("Boom");

✅ Correct​

throw new Error("Boom");

Behavior and migration notes​

This rule forwards options and behavior to unicorn/throw-new-error.

  • Lifecycle: Deprecated and frozen.
  • Deprecated since: v1.0.0
  • Available until: v2.0.0
  • Use instead: unicorn/throw-new-error

Additional examples​

throw TypeError("invalid");
// ❌ reported by forwarded unicorn rule

throw new TypeError("invalid");
// ✅ valid

ESLint flat config example​

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

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/throw-new-error": "error",
  },
 },
];

When not to use it​

Disable this rule if your codebase intentionally uses the function-call style for Error constructors.

Package documentation​

Rule catalog ID: R075

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.