no-mutable-exports.md

import/no-mutable-exports

Forbids the use of mutable exports with var or let.

Rule Details

Valid:

export const count = 1
export function getCount() {}
export class Counter {}

...whereas here exports will be reported:

export let count = 2
export var count = 3

let count = 4
export { count } // reported here

Functions/Classes

Note that exported function/class declaration identifiers may be reassigned, but are not flagged by this rule at this time. They may be in the future, if a reassignment is detected, i.e.

// possible future behavior!
export class Counter {} // reported here: exported class is reassigned on line [x].
Counter = KitchenSink // not reported here unless you enable no-class-assign

// this pre-declaration reassignment is valid on account of function hoisting
getCount = function getDuke() {} // not reported here without no-func-assign
export function getCount() {} // reported here: exported function is reassigned on line [x].

To prevent general reassignment of these identifiers, exported or not, you may want to enable the following core ESLint rules:

• no-func-assign
• no-class-assign

When Not To Use It

If your environment correctly implements mutable export bindings.