Add rule vue/no-early-return

docs/rules/README.md

@@ -223,6 +223,7 @@ For example:
 | [vue/no-bare-strings-in-template](./no-bare-strings-in-template.md) | disallow the use of bare strings in `<template>` |  | :hammer: |
 | [vue/no-boolean-default](./no-boolean-default.md) | disallow boolean defaults | :wrench: | :hammer: |
 | [vue/no-duplicate-attr-inheritance](./no-duplicate-attr-inheritance.md) | enforce `inheritAttrs` to be set to `false` when using `v-bind="$attrs"` |  | :hammer: |
+| [vue/no-early-return](./no-early-return.md) | disallow early `returns` in `setup` and `data` functions |  | :warning: |
 | [vue/no-empty-component-block](./no-empty-component-block.md) | disallow the `<template>` `<script>` `<style>` block to be empty |  | :hammer: |
 | [vue/no-multiple-objects-in-class](./no-multiple-objects-in-class.md) | disallow to pass multiple objects into array to class |  | :hammer: |
 | [vue/no-potential-component-option-typo](./no-potential-component-option-typo.md) | disallow a potential typo in your component property | :bulb: | :hammer: |

docs/rules/no-early-return.md

@@ -0,0 +1,101 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/no-early-return
+description: disallow early `returns` in `setup` and `data` functions
+---
+# vue/no-early-return
+
+> disallow early `returns` in `setup` and `data` functions
+
+- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
+
+## :book: Rule Details
+
+The `setup` and `data` functions of Vue components (and [`asyncData`](https://nuxtjs.org/docs/directory-structure/pages/#asyncdata) of Nuxt.js page components) should only have a single (unconditional) return statement at the end. This rule reports early `return` statements, i.e. those that would exit the function early without allowing to reach the end of the function body.
+
+<eslint-code-block :rules="{'vue/no-early-return': ['error']}">
+
+```vue
+<!-- ✓ GOOD -->
+<script>
+  export default {
+    setup () {
+      const foo = ref()
+      return { foo }
+    }
+  }
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/no-early-return': ['error']}">
+
+```vue
+<!-- ✗ BAD -->
+<script>
+  export default {
+    setup () {
+      const foo = ref()
+
+      if (maybe) {
+        return
+      }
+
+      for (const t of foo.value) {
+        if (t) {
+          return
+        }
+      }
+
+      return { foo }
+    }
+  }
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/no-early-return': ['error']}">
+
+```vue
+<!-- ✓ GOOD -->
+<script>
+  export default {
+    data () {
+      return { foo: true }
+    }
+  }
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/no-early-return': ['error']}">
+
+```vue
+<!-- ✗ BAD -->
+<script>
+  export default {
+    data () {
+      if (maybe) {
+        return { foo: false }
+      }
+
+      return { foo: true }
+    }
+  }
+</script>
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/no-early-return.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/no-early-return.js)

lib/index.js

@@ -86,6 +86,7 @@ module.exports = {
     'no-dupe-v-else-if': require('./rules/no-dupe-v-else-if'),
     'no-duplicate-attr-inheritance': require('./rules/no-duplicate-attr-inheritance'),
     'no-duplicate-attributes': require('./rules/no-duplicate-attributes'),
+    'no-early-return': require('./rules/no-early-return'),
     'no-empty-component-block': require('./rules/no-empty-component-block'),
     'no-empty-pattern': require('./rules/no-empty-pattern'),
     'no-export-in-script-setup': require('./rules/no-export-in-script-setup'),

lib/rules/no-early-return.js

@@ -0,0 +1,85 @@
+/**
+ * @author *****your name*****
+ * See LICENSE file in root directory for full license.
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const utils = require('../utils')
+
+const PROPERTIES_NEED_CHECKING = new Set(['data', 'asyncData'])
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow early `returns` in `setup` and `data` functions',
+      categories: undefined,
+      url: 'https://eslint.vuejs.org/rules/no-early-return.html'
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      extraReturnStatement:
+        'Only one (unconditional) return statement is allowed in {{ functionType }} function.'
+    }
+  },
+
+  /** @param {RuleContext} context */
+  create(context) {
+    const returnStatementLocations = []
+
+    return utils.defineVueVisitor(context, {
+      ReturnStatement(node) {
+        if (context.getScope().type === 'function') {
+          return
+        }
+        returnStatementLocations.push(node.loc)
+      },
+
+      onSetupFunctionExit() {
+        if (returnStatementLocations.length === 0) {
+          return
+        }
+
+        for (const loc of returnStatementLocations) {
+          context.report({
+            loc,
+            messageId: 'extraReturnStatement',
+            data: { functionType: 'setup' }
+          })
+        }
+      },
+      onVueObjectEnter(node) {
+        for (const property of PROPERTIES_NEED_CHECKING) {
+          const dataProperty = utils.findProperty(node, property)
+          if (
+            !dataProperty ||
+            (dataProperty.value.type !== 'FunctionExpression' &&
+              dataProperty.value.type !== 'ArrowFunctionExpression')
+          ) {
+            continue
+          }
+          if (
+            context
+              .getSourceCode()
+              .ast.tokens.filter((t) => t.value === 'return').length > 1
+          ) {
+            context.report({
+              node,
+              messageId: 'extraReturnStatement',
+              data: { functionType: 'data' }
+            })
+          }
+        }
+      }
+    })
+  }
+}