noThenProperty

JavaScript (and super languages)

Summary

Rule available since: v1.5.0
Diagnostic Category: lint/suspicious/noThenProperty
This rule is recommended, which means is enabled by default.
This rule doesn’t have a fix.
The default severity of this rule is error.
Sources:
- Same as unicorn/no-thenable

Description

Disallow then property.

When combining objects with a then method (thenable objects) with await expressions or dynamic imports, caution is necessary. These syntaxes interpret the object’s then method as intended for the resolution or rejection of a promise, which can lead to unexpected behavior or errors.

Examples

Invalid

1
export {then};

code-block.js:1:9 lint/suspicious/noThenProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not export then.
  
  > 1 │ export {then};
      │         ^^^^
    2 │

1
const foo = {
2
    then() {}
3
};

code-block.js:2:5 lint/suspicious/noThenProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not add then to an object.
  
    1 │ const foo = {
  > 2 │     then() {}
      │     ^^^^
    3 │ };
    4 │

1
const foo = {
2
    get then() {}
3
};

code-block.js:2:9 lint/suspicious/noThenProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not add then to an object.
  
    1 │ const foo = {
  > 2 │     get then() {}
      │         ^^^^
    3 │ };
    4 │

1
const foo = {
2
   get then() {}
3
};

code-block.js:2:8 lint/suspicious/noThenProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not add then to an object.
  
    1 │ const foo = {
  > 2 │    get then() {}
      │        ^^^^
    3 │ };
    4 │

1
foo.then = function () {}

code-block.js:1:1 lint/suspicious/noThenProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not add then to an object.
  
  > 1 │ foo.then = function () {}
      │ ^^^^^^^^
    2 │

1
class Foo {
2
    then() {}
3
}

code-block.js:2:5 lint/suspicious/noThenProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not add then to a class.
  
    1 │ class Foo {
  > 2 │     then() {}
      │     ^^^^
    3 │ }
    4 │

1
class Foo {
2
    static then() {}
3
}

code-block.js:2:12 lint/suspicious/noThenProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not add then to a class.
  
    1 │ class Foo {
  > 2 │     static then() {}
      │            ^^^^
    3 │ }
    4 │

Valid

1
export {then as success};

1
const foo = {
2
    success() {}
3
};

1
class Foo {
2
    success() {}
3
}

1
const foo = bar.then;

How to configure

1
{
2
  "linter": {
3
    "rules": {
4
      "suspicious": {
5
        "noThenProperty": "error"
6
      }
7
    }
8
  }
9
}