# functional/no-return-void 📝 Disallow functions that don't return anything. 💼 This rule is enabled in the following configs: ☑️ `lite`,  `noStatements`, ✅ `recommended`, 🔒 `strict`. 💭 This rule requires [type information](https://typescript-eslint.io/linting/typed-linting). Disallow functions that are declared as returning nothing. ## Rule Details In functional programming functions must return something, they cannot return nothing. By default, this rule allows function to return `undefined` and `null`. Note: For performance reasons, this rule does not check implicit return types. We recommend using the rule [@typescript-eslint/explicit-function-return-type](https://github.com/typescript-eslint/typescript-eslint/blob/main/packages/eslint-plugin/docs/rules/explicit-function-return-type.md) in conjunction with this rule. ### ❌ Incorrect ```ts /* eslint functional/no-return-void: "error" */ function updateText(): void {} ``` ### ✅ Correct ```ts /* eslint functional/no-return-void: "error" */ function updateText(value: string): string {} ``` ## Options This rule accepts an options object of the following type: ```ts type Options = { allowNull: boolean; allowUndefined: boolean; ignoreInferredTypes: boolean; }; ``` ### Default Options ```ts const defaults = { allowNull: true, allowUndefined: true, ignoreInferredTypes: false, }; ``` ### `allowNull` If true allow returning null. ### `allowUndefined` If true allow returning undefined. ### `ignoreInferredTypes` If true ignore functions that don't explicitly specify a return type.