> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt
> Use this file to discover all available pages before exploring further.
# JavaScript Re-Export
Re-exporting in JavaScript is the process of forwarding module bindings from one module through another without importing those bindings into the current module's local scope. It combines the `import` and `export` declarations into a single statement, allowing a module to act as a pass-through for variables, functions, or classes defined in a different file.
Because re-exported bindings are never evaluated in the local scope of the forwarding module, they cannot be accessed or manipulated by the forwarding module itself.
## Syntax Variations
JavaScript provides several syntactic forms for re-exporting, depending on whether you are handling named exports, default exports, or entire module namespaces.
### 1. Named Re-exports
You can selectively forward specific named exports from a target module. You can also alias these exports during the pass-through using the `as` keyword.
```javascript theme={"dark"}
// Forward specific named exports exactly as they are
export { foo, bar } from './moduleA.js';
// Forward specific named exports under new identifiers (aliasing)
export { foo as newFoo, bar as newBar } from './moduleA.js';
```
### 2. Namespace Re-exports
You can forward all named exports from a target module using the `*` wildcard.
```javascript theme={"dark"}
// Forward all named exports from moduleA
export * from './moduleA.js';
// Forward all named exports as a single namespace object (Introduced in ES2020)
export * as moduleANamespace from './moduleA.js';
```
*Note: The `export * from './moduleA.js'` syntax explicitly ignores the `default` export of `moduleA.js`. It only forwards named exports.*
### 3. Default Re-exports
Handling default exports requires explicit syntax, as the `default` keyword is treated as a specific named binding in the ES module system.
```javascript theme={"dark"}
// Forward the target's default export as this module's default export
export { default } from './moduleA.js';
// Forward the target's default export as a named export
export { default as moduleADefault } from './moduleA.js';
// Forward a target's named export as this module's default export
export { foo as default } from './moduleA.js';
```
## Technical Constraints and Behavior
* **Scope Isolation:** If you write `export { foo } from './moduleA.js';`, the identifier `foo` is not declared in the current file. Attempting to `console.log(foo)` in the forwarding file will result in a `ReferenceError`.
* **Name Collisions:** If you use `export * from './moduleA.js'` and `export * from './moduleB.js'`, and both modules export a binding with the same name, JavaScript will not throw an error immediately. However, a `SyntaxError` will be thrown when another module attempts to import the conflicted binding from the forwarding module.
* **Live Bindings:** Like standard exports, re-exports maintain live bindings to the original module. If the value of a re-exported variable changes in the originating module, that change is reflected wherever the re-export is consumed.
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