# No top level state (no-top-level-state) Disallow top level state. State at the top level indicates side effects because if used by functions or methods their behavior may change over time. This is not always problematic (e.g. a cache) but should be used sparingly and intentionally. ## Rule Details This rule lets you control top level state. For to historical reasons, some of this is managed by the [`no-top-level-variables` rule] instead. To avoid top level state make sure to configure both rules. Examples of **incorrect** code for this rule: ```javascript const glob = /foobar/g; // The 'g' flag makes the regular expression stateful const stic = /foobar/y; // The 'y' flag makes the regular expression stateful ``` Examples of **correct** code for this rule: ```javascript const regexp = /foobar/; ``` ### Options This rule does not have any configuration. ## When Not To Use It If you want to allow top level state. --- Please [open an issue] if you found a mistake or if you have a suggestion for how to improve the documentation. [open an issue]: https://github.com/ericcornelissen/eslint-plugin-top/issues/new?labels=documentation&template=documentation.md [`no-top-level-variables` rule]: ./no-top-level-variables.md