Implement PartialEq for JsValue (#217)

Dispatch to JS's `===` operator internally

crates/cli-support/src/js/mod.rs

@@ -300,6 +300,15 @@ impl<'a> Context<'a> {
             "))
         })?;
 
+        self.bind("__wbindgen_jsval_eq", &|me| {
+            me.expose_get_object();
+            Ok(String::from("
+                function(a, b) {
+                    return getObject(a) === getObject(b) ? 1 : 0;
+                }
+            "))
+        })?;
+
         self.unexport_unused_internal_exports();
         self.gc()?;
 

src/lib.rs

@@ -243,6 +243,14 @@ impl JsValue {
     }
 }
 
+impl PartialEq for JsValue {
+    fn eq(&self, other: &JsValue) -> bool {
+        unsafe {
+            __wbindgen_jsval_eq(self.idx, other.idx) != 0
+        }
+    }
+}
+
 impl<'a> From<&'a str> for JsValue {
     fn from(s: &'a str) -> JsValue {
         JsValue::from_str(s)
@@ -317,6 +325,7 @@ externs! {
 
     fn __wbindgen_json_parse(ptr: *const u8, len: usize) -> u32;
     fn __wbindgen_json_serialize(idx: u32, ptr: *mut *mut u8) -> usize;
+    fn __wbindgen_jsval_eq(a: u32, b: u32) -> u32;
 }
 
 impl Clone for JsValue {

tests/all/api.rs

@@ -142,3 +142,41 @@ fn works() {
         .test();
 }
 
+#[test]
+fn eq_works() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            pub fn test(a: &JsValue, b: &JsValue) -> bool {
+                a == b
+            }
+
+            #[wasm_bindgen]
+            pub fn test1(a: &JsValue) -> bool {
+                a == a
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                assert.strictEqual(wasm.test('a', 'a'), true);
+                assert.strictEqual(wasm.test('a', 'b'), false);
+                assert.strictEqual(wasm.test(NaN, NaN), false);
+                assert.strictEqual(wasm.test({a: 'a'}, {a: 'a'}), false);
+                assert.strictEqual(wasm.test1(NaN), false);
+                let x = {a: 'a'};
+                assert.strictEqual(wasm.test(x, x), true);
+                assert.strictEqual(wasm.test1(x), true);
+            }
+        "#)
+        .test();
+}
+