Skip to main content

sort-call-signature

Require call signatures to be the first member in interfaces.

Targeted pattern scope​

This rule targets interface call signatures that are not the first member in a TSInterfaceBody.

What this rule reports​

This rule reports interface call signatures when they are not the first member in the interface body.

Why this rule exists​

Placing call signatures first gives function-like interfaces a consistent, discoverable shape.

❌ Incorrect​

interface I {
 x: string;
 (): string;
}

✅ Correct​

interface I {
 (): string;
 x: string;
}

Behavior and migration notes​

This rule reports only and does not provide an autofix.

Migration is mechanical: move call signatures above other members in each affected interface.

Options​

This rule has no options.

Additional examples​

interface Factory {
 new (): FactoryInstance;
 (): FactoryInstance;
 version: string;
}
// ❌ call signature is not first

interface FactoryFixed {
 (): FactoryInstance;
 new (): FactoryInstance;
 version: string;
}
// ✅ valid

ESLint flat config example​

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

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/sort-call-signature": "error",
  },
 },
];

When not to use it​

Disable this rule if interface member order is not important in your style guide.

Package documentation​

Rule catalog ID: R066

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.