Add JS::Object#typeof method to test object type

ext/js/bindgen/rb-js-abi-host.wit

@@ -14,6 +14,8 @@ js-value-to-string: function(value: js-abi-value) -> string
 export-js-value-to-host: function(value: js-abi-value)
 import-js-value-from-host: function() -> js-abi-value
 
+js-value-typeof: function(value: js-abi-value) -> string
+
 reflect-apply: function(target: js-abi-value, this-argument: js-abi-value, arguments: list<js-abi-value>) -> js-abi-value
 reflect-construct: function(target: js-abi-value, arguments: list<js-abi-value>) -> js-abi-value
 reflect-delete-property: function(target: js-abi-value, property-key: string) -> bool

ext/js/js-core.c

@@ -218,6 +218,25 @@ static VALUE _rb_js_obj_call(int argc, VALUE *argv, VALUE obj) {
       rb_js_abi_host_reflect_apply(abi_method->abi, p->abi, &abi_args));
 }
 
+/*
+ * call-seq:
+ *  js_value.typeof -> String
+ *
+ * Returns the result string of JavaScript 'typeof' operator.
+ * See also JS.is_a? for 'instanceof' operator.
+ *   p JS.global.typeof                     # => "object"
+ *   p JS.eval("return 1").typeof           # => "number"
+ *   p JS.eval("return 'str'").typeof       # => "string"
+ *   p JS.eval("return undefined").typeof   # => "undefined"
+ *   p JS.eval("return null").typeof        # => "object"
+ */
+static VALUE _rb_js_obj_typeof(VALUE obj) {
+  struct jsvalue *p = check_jsvalue(obj);
+  rb_js_abi_host_string_t ret0;
+  rb_js_abi_host_js_value_typeof(p->abi, &ret0);
+  return rb_str_new(ret0.ptr, ret0.len);
+}
+
 /*
  * call-seq:
  *   inspect -> string
@@ -319,6 +338,7 @@ void Init_js() {
   rb_define_method(rb_cJS_Object, "[]", _rb_js_obj_aref, 1);
   rb_define_method(rb_cJS_Object, "[]=", _rb_js_obj_aset, 2);
   rb_define_method(rb_cJS_Object, "call", _rb_js_obj_call, -1);
+  rb_define_method(rb_cJS_Object, "typeof", _rb_js_obj_typeof, 0);
   rb_define_method(rb_cJS_Object, "__export_to_js", _rb_js_export_to_js, 0);
   rb_define_singleton_method(rb_cJS_Object, "__import_from_js", _rb_js_import_from_js, 0);
   rb_define_method(rb_cJS_Object, "inspect", _rb_js_obj_inspect, 0);

packages/npm-packages/ruby-wasm-wasi/src/index.ts

@@ -120,6 +120,9 @@ export class RubyVM {
             return false;
           }
         },
+        jsValueTypeof(value) {
+          return typeof value;
+        },
         reflectApply: function (target, thisArgument, args) {
           return Reflect.apply(target as any, thisArgument, args);
         },

packages/npm-packages/ruby-wasm-wasi/test/js_from_rb.test.ts

@@ -24,6 +24,18 @@ describe("Manipulation of JS from Ruby", () => {
     expect(vm.eval(code).toString()).toBe(String(props.result));
   });
 
+  test.each([
+    { object: `JS.eval('return 1')`, result: "number" },
+    { object: `JS.eval('return "x"')`, result: "string" },
+    { object: `JS.eval('return null')`, result: "object" },
+    { object: `JS.eval('return undefined')`, result: "undefined" },
+    { object: `JS.global`, result: "object" },
+  ])("JS::Object#typeof (%s)", async (props) => {
+    const vm = await initRubyVM();
+    const code = `require "js"; (${props.object}).typeof`;
+    expect(vm.eval(code).toString()).toBe(String(props.result));
+  });
+
   test.each([
     { expr: "JS.global[:Object]", result: Object },
     { expr: "JS.global[:Object][:keys]", result: Object.keys },