LibJS: Implement ECMA-402 compliant TypedArray.prototype.toLocaleString

Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp

@@ -1290,23 +1290,56 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::map)
 }
 
 // 23.2.3.29 %TypedArray%.prototype.toLocaleString ( [ reserved1 [ , reserved2 ] ] ), https://tc39.es/ecma262/#sec-%typedarray%.prototype.tolocalestring
+// 18.5.1 Array.prototype.toLocaleString ( [ locales [ , options ] ] ), https://tc39.es/ecma402/#sup-array.prototype.tolocalestring
 JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::to_locale_string)
 {
+    auto locales = vm.argument(0);
+    auto options = vm.argument(1);
+
+    // This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm.
+    // If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.
     auto* typed_array = TRY(validate_typed_array_from_this(global_object));
 
+    // 1. Let array be ? ToObject(this value).
+    // NOTE: Handled by ValidateTypedArray
+
+    // 2. Let len be ? ToLength(? Get(array, "length")).
+    // The implementation of the algorithm may be optimized with the knowledge that the this value is an object that
+    // has a fixed length and whose integer-indexed properties are not sparse.
     auto length = typed_array->array_length();
 
+    // 3. Let separator be the String value for the list-separator String appropriate for the host environment's current locale (this is derived in an implementation-defined way).
+    constexpr auto separator = ',';
+
+    // 4. Let R be the empty String.
     StringBuilder builder;
-    for (u32 k = 0; k < length; ++k) {
-        if (k > 0)
-            builder.append(','); // NOTE: Until we implement ECMA-402 (Intl) this is implementation specific.
-        auto value = TRY(typed_array->get(k));
-        if (value.is_nullish())
-            continue;
-        auto locale_string_result = TRY(value.invoke(global_object, vm.names.toLocaleString));
-        auto string = TRY(locale_string_result.to_string(global_object));
-        builder.append(string);
+
+    // 5. Let k be 0.
+    // 6. Repeat, while k < len,
+    for (size_t k = 0; k < length; ++k) {
+        // a. If k > 0, then
+        if (k > 0) {
+            // i. Set R to the string-concatenation of R and separator.
+            builder.append(separator);
+        }
+
+        // b. Let nextElement be ? Get(array, ! ToString(k)).
+        auto next_element = TRY(typed_array->get(k));
+
+        // c. If nextElement is not undefined or null, then
+        if (!next_element.is_nullish()) {
+            // i. Let S be ? ToString(? Invoke(nextElement, "toLocaleString", « locales, options »)).
+            auto locale_string_value = TRY(next_element.invoke(global_object, vm.names.toLocaleString, locales, options));
+            auto locale_string = TRY(locale_string_value.to_string(global_object));
+
+            // ii. Set R to the string-concatenation of R and S.
+            builder.append(locale_string);
+        }
+
+        // d. Increase k by 1.
     }
+
+    // 7. Return R.
     return js_string(vm, builder.to_string());
 }