LibJS: Add Object.prototype.toLocaleString()

Author: https://github.com/linusg
Commit: https://github.com/SerenityOS/serenity/commit/70d2add22f7
Pull-request: https://github.com/SerenityOS/serenity/pull/2431
Reviewed-by: https://github.com/awesomekling ✅

Libraries/LibJS/Runtime/ObjectPrototype.cpp

@@ -45,6 +45,7 @@ void ObjectPrototype::initialize()
     u8 attr = Attribute::Writable | Attribute::Configurable;
     define_native_function("hasOwnProperty", has_own_property, 1, attr);
     define_native_function("toString", to_string, 0, attr);
+    define_native_function("toLocaleString", to_locale_string, 0, attr);
     define_native_function("valueOf", value_of, 0, attr);
 }
 
@@ -71,6 +72,14 @@ Value ObjectPrototype::to_string(Interpreter& interpreter)
     return js_string(interpreter, String::format("[object %s]", this_object->class_name()));
 }
 
+Value ObjectPrototype::to_locale_string(Interpreter& interpreter)
+{
+    auto* this_object = interpreter.this_value().to_object(interpreter);
+    if (!this_object)
+        return {};
+    return this_object->invoke("toString");
+}
+
 Value ObjectPrototype::value_of(Interpreter& interpreter)
 {
     auto* this_object = interpreter.this_value().to_object(interpreter);

Libraries/LibJS/Runtime/ObjectPrototype.h

@@ -44,6 +44,7 @@ private:
     virtual const char* class_name() const override { return "ObjectPrototype"; }
 
     static Value has_own_property(Interpreter&);
+    static Value to_locale_string(Interpreter&);
     static Value value_of(Interpreter&);
 };
 

Libraries/LibJS/Tests/Object.prototype.toLocaleString.js

@@ -0,0 +1,32 @@
+load("test-common.js");
+
+try {
+    assert(Object.prototype.toLocaleString.length === 0);
+
+    var o;
+
+    o = {};
+    assert(o.toString() === o.toLocaleString());
+
+    o = { toString: () => 42 };
+    assert(o.toString() === 42);
+
+    o = { toString: () => { throw Error(); } };
+    assertThrowsError(() => {
+        o.toLocaleString();
+    }, {
+        error: Error
+    });
+
+    o = { toString: "foo" };
+    assertThrowsError(() => {
+        o.toLocaleString();
+    }, {
+        error: TypeError,
+        message: "foo is not a function"
+    });
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}