import/prefer-default-export ​
In exporting files, this rule checks if there is default export or not.
Rule Details ​
rule schema ​
javascript
"import/prefer-default-export": [
( "off" | "warn" | "error" ),
{ "target": "single" | "any" } // default is "single"
]Config Options ​
There are two options available: single and any. By default, if you do not specify the option, rule will assume it is single.
single ​
Definition: When there is only a single export from a module, prefer using default export over named export.
How to setup config file for this rule:
javascript
// you can manually specify it
"rules": {
"import/prefer-default-export": [
( "off" | "warn" | "error" ),
{ "target": "single" }
]
}
// config setup below will also work
"rules": {
"import/prefer-default-export": "off" | "warn" | "error"
}The following patterns are considered warnings:
javascript
// bad.js
// There is only a single module export and it's a named export.
export const foo = 'foo';The following patterns are not warnings:
javascript
// good1.js
// There is a default export.
export const foo = 'foo';
const bar = 'bar';
export default bar;javascript
// good2.js
// There is more than one named export in the module.
export const foo = 'foo';
export const bar = 'bar';javascript
// good3.js
// There is more than one named export in the module
const foo = 'foo';
const bar = 'bar';
export { foo, bar }javascript
// good4.js
// There is a default export.
const foo = 'foo';
export { foo as default }javascript
// export-star.js
// Any batch export will disable this rule. The remote module is not inspected.
export * from './other-module'any ​
Definition: any exporting file must contain a default export.
How to setup config file for this rule:
javascript
// you have to manually specify it
"rules": {
"import/prefer-default-export": [
( "off" | "warn" | "error" ),
{ "target": "any" }
]
}The following patterns are not considered warnings:
javascript
// good1.js
//has default export
export default function bar() {};javascript
// good2.js
// has default export
let foo;
export { foo as default }javascript
// good3.js
//contains multiple exports AND default export
export const a = 5;
export function bar(){};
let foo;
export { foo as default }javascript
// good4.js
// does not contain any exports => file is not checked by the rule
import * as foo from './foo';javascript
// export-star.js
// Any batch export will disable this rule. The remote module is not inspected.
export * from './other-module'The following patterns are considered warnings:
javascript
// bad1.js
//has 2 named exports, but no default export
export const foo = 'foo';
export const bar = 'bar';javascript
// bad2.js
// does not have default export
let foo, bar;
export { foo, bar }javascript
// bad3.js
// does not have default export
export { a, b } from "foo.js"javascript
// bad4.js
// does not have default export
let item;
export const foo = item;
export { item };