| | import { defineRule } from '../utils/define-rule' |
| | const url = 'https://nextjs.org/docs/messages/no-duplicate-head' |
| |
|
| | export = defineRule({ |
| | meta: { |
| | docs: { |
| | description: |
| | 'Prevent duplicate usage of `<Head>` in `pages/_document.js`.', |
| | recommended: true, |
| | url, |
| | }, |
| | type: 'problem', |
| | schema: [], |
| | }, |
| | create(context) { |
| | const { sourceCode } = context |
| | let documentImportName |
| | return { |
| | ImportDeclaration(node) { |
| | if (node.source.value === 'next/document') { |
| | const documentImport = node.specifiers.find( |
| | ({ type }) => type === 'ImportDefaultSpecifier' |
| | ) |
| | if (documentImport && documentImport.local) { |
| | documentImportName = documentImport.local.name |
| | } |
| | } |
| | }, |
| | ReturnStatement(node) { |
| | const ancestors = sourceCode.getAncestors(node) |
| | const documentClass = ancestors.find( |
| | (ancestorNode) => |
| | ancestorNode.type === 'ClassDeclaration' && |
| | ancestorNode.superClass && |
| | 'name' in ancestorNode.superClass && |
| | ancestorNode.superClass.name === documentImportName |
| | ) |
| |
|
| | if (!documentClass) { |
| | return |
| | } |
| |
|
| | if ( |
| | node.argument && |
| | 'children' in node.argument && |
| | node.argument.children |
| | ) { |
| | |
| | const headComponents = node.argument.children.filter( |
| | (childrenNode) => |
| | childrenNode.openingElement && |
| | childrenNode.openingElement.name && |
| | childrenNode.openingElement.name.name === 'Head' |
| | ) |
| |
|
| | if (headComponents.length > 1) { |
| | for (let i = 1; i < headComponents.length; i++) { |
| | context.report({ |
| | node: headComponents[i], |
| | message: `Do not include multiple instances of \`<Head/>\`. See: ${url}`, |
| | }) |
| | } |
| | } |
| | } |
| | }, |
| | } |
| | }, |
| | }) |
| |
|
