no-thenable.md

Disallow then property

💼 This rule is enabled in the ✅ recommended config.

If an object is defined as "thenable", once it's accidentally used in an await expression, it may cause problems:

const foo = {
	unicorn: 1,
	then() {},
};

const {unicorn} = await foo;

console.log('after'); //<- This will never execute

const foo = {
	unicorn: 1,
	then() {
		throw new Error('You shouldn’t have called me')
	},
};

const {unicorn} = await foo;
// Error: You shouldn’t have called me

If a module has an export named then, dynamic import() may not work as expected:

// foo.js

export function then () {
	throw new Error('You shouldn’t have called me')
}

// bar.js

const foo = await import('./foo.js');
// Error: You shouldn’t have called me

Fail

export {then};

const foo = {
	then() {}
};

const foo = {
	get then() {}
};

foo.then = function () {}

class Foo {
	then() {}
}

class Foo {
	static then() {}
}

Pass

export {then as success};

const foo = {
	success() {}
};

class Foo {
	success() {}
}

const foo = bar.then;