# `constructor`
When attached to a Rust "constructor" it will make the generated JavaScript
bindings callable as `new Foo()`.
For example, consider this exported Rust type and `constructor` annotation:
```rust
#[wasm_bindgen]
pub struct Foo {
contents: u32,
}
#[wasm_bindgen]
impl Foo {
#[wasm_bindgen(constructor)]
pub fn new() -> Foo {
Foo { contents: 0 }
}
pub fn get_contents(&self) -> u32 {
self.contents
}
}
```
This can be used in JavaScript as:
```js
import { Foo } from './my_module';
const f = new Foo();
console.log(f.get_contents());
```