exportMutables

Reports exporting mutable bindings (let or var).

✅ This rule is included in the ts logical presets.

Exporting mutable bindings (let or var) can lead to confusing behavior. When an exported variable is changed, consumers of the module will see the updated value, which can be unexpected and difficult to debug.

This rule requires exported variables to be declared with const to ensure they cannot be reassigned.

Examples

❌ Incorrect

export let counter = 0;

export var name = "default";

✅ Correct

export const counter = 0;

export const name = "default";

let internalCounter = 0;

export function getCounter() {
  return internalCounter;
}

export function increment() {
  internalCounter++;
}

When Mutation Is Necessary

If you need to expose a value that changes over time, consider these alternatives:

• Export getter and setter functions
• Export an object with methods to access and modify the value
• Use a state management pattern

Options

This rule is not configurable.

When Not To Use It

If you intentionally use mutable exports for module-level state that consumers are expected to observe, you may disable this rule. However, this pattern can be confusing and is generally discouraged.

Further Reading

• MDN: export

Equivalents in Other Linters

• ESLint: import/no-mutable-exports
• Oxlint: import/no-mutable-exports