{"record":{"id":"db486f2613d7edae","repo":"oxc-project/oxc","slug":"do-not-include-multiple-instances-of-head","errorCode":null,"errorMessage":"Do not include multiple instances of `
`","messagePattern":"Do not include multiple instances of ``","errorType":"validation","errorClass":"OxcDiagnostic","httpStatus":null,"severity":"warning","filePath":"crates/oxc_linter/src/rules/nextjs/no_duplicate_head.rs","lineNumber":10,"sourceCode":"use oxc_ast::AstKind;\nuse oxc_diagnostics::{LabeledSpan, OxcDiagnostic};\nuse oxc_macros::declare_oxc_lint;\nuse oxc_semantic::AstNode;\nuse oxc_span::GetSpan;\n\nuse crate::{context::LintContext, rule::Rule};\n\nfn no_duplicate_head(labels: Vec) -> OxcDiagnostic {\n OxcDiagnostic::warn(\"Do not include multiple instances of ``\")\n .with_help(\"Only use a single `` component in your custom document in `pages/_document.js`. See: https://nextjs.org/docs/messages/no-duplicate-head\")\n .with_labels(labels)\n}\n#[derive(Debug, Default, Clone)]\npub struct NoDuplicateHead;\n\ndeclare_oxc_lint!(\n /// ### What it does\n ///\n /// Prevent duplicate usage of `` in `pages/_document.js`.\n ///\n /// ### Why is this bad?\n ///\n /// This can cause unexpected behavior in your application.\n ///\n /// ### Examples\n ///\n /// Examples of **incorrect** code for this rule:","sourceCodeStart":1,"sourceCodeEnd":28,"githubUrl":"https://github.com/oxc-project/oxc/blob/e1e7af627c8843ab64044ed466b128fcc21a035b/crates/oxc_linter/src/rules/nextjs/no_duplicate_head.rs#L1-L28","documentation":"Warning from oxlint rule `nextjs/no-duplicate-head`. In `pages/_document.js`, each `` imported from `next/document` produces its own server-rendered head context; more than one yields duplicate or conflicting head markup. The rule counts `Head` usages in the custom document and, when there are two or more, reports every occurrence with a label on each.","triggerScenarios":"Two or more `...` elements (from `next/document`) rendered anywhere in `pages/_document.js`, including inside fragments or conditionals.","commonSituations":"Splitting the document into sections and giving each its own ``; pasting a meta block into a second Head; merging markup from two tutorials.","solutions":["Merge the children of every `` block into a single `` in `_document.js`.","Keep only document-wide tags (charset, viewport) there; move page-specific tags to `next/head` in each page."],"exampleFix":"// before\n\n \n