unicorn/no-instanceof-builtins Suspicious

🚧 An auto-fix is still under development.

Disallows the use of instanceof with ECMAScript built-in constructors because:

it breaks across execution contexts (iframe, Web Worker, Node VM, etc.);
it is often misleading (e.g. instanceof Array fails for a subclass);
there is always a clearer and safer alternative (Array.isArray, typeof, Buffer.isBuffer, …).

instanceof breaks across execution contexts (iframe, Web Worker, Node vm), and may give misleading results for subclasses or exotic objects.

Examples of incorrect code for this rule:

javascript

if (arr instanceof Array) { … }
if (el instanceof HTMLElement) { … }

Examples of correct code for this rule:

javascript

if (Array.isArray(arr)) { … }
if (el?.nodeType === 1) { … }

How to use

To enable this rule in the CLI or using the config file, you can use:

CLIConfig (.oxlintrc.json)

bash

oxlint --deny unicorn/no-instanceof-builtins

json

{
  "rules": {
    "unicorn/no-instanceof-builtins": "error"
  }
}