oxc-project/oxc · error · OxcDiagnostic

`React` must be in scope when using JSX.

Error message

`React` must be in scope when using JSX.

What it means

Raised by react/react_in_jsx_scope when JSX is compiled with the classic `React.createElement` transform but no `React` binding is reachable in the module's scope. At the throw site the generated code will reference an undefined `React` identifier and crash at runtime ('React is not defined'); the diagnostic marks the JSX span where the missing reference originates. run() resolves JSX element references against the semantic scope tree and reports when the `React` import/require is absent.

Source

Thrown at crates/oxc_linter/src/rules/react/react_in_jsx_scope.rs:14

use oxc_ast::AstKind;
use oxc_diagnostics::OxcDiagnostic;
use oxc_macros::declare_oxc_lint;
use oxc_span::{GetSpan, Span};
use oxc_str::static_ident;

use crate::{
    AstNode,
    context::{ContextHost, LintContext},
    rule::Rule,
};

fn react_in_jsx_scope_diagnostic(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("`React` must be in scope when using JSX.")
        .with_help("When using JSX, `<a />` expands to `React.createElement(\"a\")`. Therefore the `React` variable must be in scope.")
        .with_label(span)
}

#[derive(Debug, Default, Clone)]
pub struct ReactInJsxScope;

declare_oxc_lint!(
    /// ### What it does
    ///
    /// Enforces that React is imported and in-scope when using JSX syntax.
    ///
    /// Note that this rule is **not necessary** on React 17+ if you are using
    /// the new JSX Transform, and you can disable this rule and skip importing
    /// `React` in files with JSX syntax.
    ///
    /// If your `tsconfig.json` has `jsx` set to `react-jsx` or `react-jsxdev`, you are using the new JSX Transform.
    /// For JavaScript projects using Babel, you are using the new JSX Transform if your React preset configuration

View on GitHub (pinned to e1e7af627c)

Solutions

1. Add `import React from "react"` at the top of the file.
2. Migrate to the automatic JSX runtime (jsx: react-jsx) and disable this rule.

When it happens

Trigger: Thrown at crates/oxc_linter/src/rules/react/react_in_jsx_scope.rs:14 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of oxc-project/oxc@e1e7af627c (2026-08-20). Data as JSON: /api/errors/d1b94426f4af2cf6. Report an issue: GitHub.