oxc-project/oxc · warning

Prefer default export to be present on every file that has e

Error message

Prefer default export to be present on every file that has export.

What it means

This is oxlint's 'import/prefer-default-export' diagnostic in its non-default "any" target mode. With { "target": "any" }, the rule demands a default export from every module that has any exports at all, so a file with only named exports is reported. The message and help text point you to adding a default export.

Source

Thrown at crates/oxc_linter/src/rules/import/prefer_default_export.rs:19

use oxc_diagnostics::OxcDiagnostic;
use oxc_macros::declare_oxc_lint;
use oxc_span::Span;
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use serde_json::Value;

use crate::{
    context::LintContext,
    module_record::ExportEntry,
    rule::{DefaultRuleConfig, Rule},
};

fn prefer_default_export_diagnostic(span: Span, target: Target) -> OxcDiagnostic {
    let msg = if target == Target::Single {
        "Prefer default export on a file with single export."
    } else {
        "Prefer default export to be present on every file that has export."
    };
    OxcDiagnostic::warn(msg).with_help("Prefer a default export").with_label(span)
}

#[derive(Debug, Default, PartialEq, Clone, Copy, Deserialize, Serialize, JsonSchema)]
#[serde(rename_all = "kebab-case")]
enum Target {
    /// Prefer default export when there is only one export in the module.
    #[default]
    Single,
    /// Prefer default export in any module that has exports.
    Any,
}

#[derive(Debug, Default, Clone, Deserialize, Serialize, JsonSchema)]
#[serde(rename_all = "camelCase", default, deny_unknown_fields)]
pub struct PreferDefaultExport {
    /// Configuration option to specify the target type for preferring default exports.
    target: Target,

View on GitHub (pinned to e1e7af627c)

Solutions

1. Add a default export to the module that exposes its primary entity (e.g. export default mainComponent alongside named helpers).
2. If the file is a barrel (index.ts re-exports), exclude it from the rule via overrides in .oxlintrc.json.
3. If your team actually prefers named exports, change the config back to the default target "single" or disable the rule.
4. Inline-suppress deliberate exceptions with // oxlint-disable-next-line import/prefer-default-export.

Example fix

// before (utils.ts)
export function clamp(n: number, min: number, max: number) { /* ... */ }

// after (utils.ts)
export function clamp(n: number, min: number, max: number) { /* ... */ }
export default { clamp };

When it happens

Trigger: Configure the rule as "import/prefer-default-export": ["error", { "target": "any" }] and lint a module that has at least one export entry but no default export entry. The diagnostic's span covers the offending export.

Common situations: Teams that standardize on default exports (many Angular or older React codebases) enable target "any" during lint migrations and get flooded with reports on barrel files and pure named-export utility modules. Accidentally configuring target "any" when the single mode was intended is also common.

Related errors

• Prefer default export on a file with single export.
• Exporting mutable '{kind_str}' binding, use 'const' instead.
• Tried to get an allocator from an empty `FixedSizeAllocatorP
• Prefer using inline type specifiers instead of a top-level t
• Prefer using a top-level type-only import instead of inline

AI-assisted analysis of oxc-project/oxc@e1e7af627c (2026-08-20). Data as JSON: /api/errors/9dc4948de239a6f3. Report an issue: GitHub.