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+# napi
+
+This directory contains source for Deno's Node-API implementation. It depends on
+`napi_sym` and `deno_napi`.
+
+Files are generally organized the same as in Node.js's implementation to ease in
+ensuring compatibility.
+
+## Adding a new function
+
+Add the symbol name to
+[`cli/napi_sym/symbol_exports.json`](../napi_sym/symbol_exports.json).
+
+```diff
+{
+  "symbols": [
+    ...
+    "napi_get_undefined",
+-   "napi_get_null"
++   "napi_get_null",
++   "napi_get_boolean"
+  ]
+}
+```
+
+Determine where to place the implementation. `napi_get_boolean` is related to JS
+values so we will place it in `js_native_api.rs`. If something is not clear,
+just create a new file module.
+
+See [`napi_sym`](../napi_sym/) for writing the implementation:
+
+```rust
+#[napi_sym::napi_sym]
+fn napi_get_boolean(
+  env: *mut Env,
+  value: bool,
+  result: *mut napi_value,
+) -> Result {
+  // ...
+  Ok(())
+}
+```
+
+Update the generated symbol lists using the script:
+
+```
+deno run --allow-write tools/napi/generate_symbols_lists.js
+```
+
+Add a test in [`/tests/napi`](../../tests/napi/). You can also refer to Node.js
+test suite for Node-API.
+
+```js
+// tests/napi/boolean_test.js
+import { assertEquals, loadTestLibrary } from "./common.js";
+const lib = loadTestLibrary();
+Deno.test("napi get boolean", function () {
+  assertEquals(lib.test_get_boolean(true), true);
+  assertEquals(lib.test_get_boolean(false), false);
+});
+```
+
+```rust
+// tests/napi/src/boolean.rs
+
+use napi_sys::Status::napi_ok;
+use napi_sys::ValueType::napi_boolean;
+use napi_sys::*;
+
+extern "C" fn test_boolean(
+  env: napi_env,
+  info: napi_callback_info,
+) -> napi_value {
+  let (args, argc, _) = crate::get_callback_info!(env, info, 1);
+  assert_eq!(argc, 1);
+
+  let mut ty = -1;
+  assert!(unsafe { napi_typeof(env, args[0], &mut ty) } == napi_ok);
+  assert_eq!(ty, napi_boolean);
+
+  // Use napi_get_boolean here...
+
+  value
+}
+
+pub fn init(env: napi_env, exports: napi_value) {
+  let properties = &[crate::new_property!(env, "test_boolean\0", test_boolean)];
+
+  unsafe {
+    napi_define_properties(env, exports, properties.len(), properties.as_ptr())
+  };
+}
+```
+
+```diff
+// tests/napi/src/lib.rs
+
++ mod boolean;
+
+...
+
+#[no_mangle]
+unsafe extern "C" fn napi_register_module_v1(
+  env: napi_env,
+  exports: napi_value,
+) -> napi_value {
+  ...
++ boolean::init(env, exports);
+
+  exports
+}
+```
+
+Run the test using `cargo test -p tests/napi`.