web-sys crate 具有以下檔案和目錄配置

.
├── build.rs
├── Cargo.toml
├── README.md
├── src
│   └── lib.rs
└── webidls
    └── enabled
        └── ...

這些是我們將實際產生綁定的 WebIDL 介面（或至少是這些檔案中定義的某些事物的綁定）。

build.rs 在 webidls/enabled 中的所有 WebIDL 檔案上調用 wasm-bindgen 的 WebIDL 前端。它將產生的綁定寫入 cargo build 的輸出目錄。

src/lib.rs 唯一做的事情是在編譯時包含在 build.rs 中產生的綁定。這是完整的 src/lib.rs 檔案

# #![allow(unused_variables)]
#fn main() {
//! Raw API bindings for Web APIs
//!
//! This is a procedurally generated crate from browser WebIDL which provides a
//! binding to all APIs that browsers provide on the web.
//!
//! This crate by default contains very little when compiled as almost all of
//! its exposed APIs are gated by Cargo features. The exhaustive list of
//! features can be found in `crates/web-sys/Cargo.toml`, but the rule of thumb
//! for `web-sys` is that each type has its own cargo feature (named after the
//! type). Using an API requires enabling the features for all types used in the
//! API, and APIs should mention in the documentation what features they
//! require.

#![doc(html_root_url = "https://docs.rs/web-sys/0.3")]
#![no_std]
#![allow(deprecated)]

extern crate alloc;

mod features;
#[allow(unused_imports)]
pub use features::*;

pub use js_sys;
pub use wasm_bindgen;

/// Getter for the `Window` object
///
/// [MDN Documentation]
///
/// *This API requires the following crate features to be activated: `Window`*
///
/// [MDN Documentation]: https://developer.mozilla.org/en-US/docs/Web/API/Window
#[cfg(feature = "Window")]
pub fn window() -> Option<Window> {
    use wasm_bindgen::JsCast;

    js_sys::global().dyn_into::<Window>().ok()
}

#}

編譯時，crate 預設幾乎是空的，這可能不是您想要的！由於 API 的數量非常龐大，此 crate 使用功能來啟用其 API 的某些部分，以減少編譯時間。Cargo.toml 中的功能列表都對應於生成的函數中的類型。啟用某個功能就會啟用該類型。所有方法都應指出需要激活哪些功能才能使用該方法。