LibJS: Add spec comments to NumberConstructor

1 files changed, 27 insertions, 9 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/NumberConstructor.cpp b/Userland/Libraries/LibJS/Runtime/NumberConstructor.cpp
index d061171e7a..6f11164b89 100644
--- a/Userland/Libraries/LibJS/Runtime/NumberConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/NumberConstructor.cpp
@@ -108,30 +108,48 @@ ThrowCompletionOr<NonnullGCPtr<Object>> NumberConstructor::construct(FunctionObj
 // 21.1.2.2 Number.isFinite ( number ), https://tc39.es/ecma262/#sec-number.isfinite
 JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_finite)
 {
-    return Value(vm.argument(0).is_finite_number());
+    auto number = vm.argument(0);
+
+    // 1. If number is not a Number, return false.
+    // 2. If number is not finite, return false.
+    // 3. Otherwise, return true.
+    return Value(number.is_finite_number());
 }
 
 // 21.1.2.3 Number.isInteger ( number ), https://tc39.es/ecma262/#sec-number.isinteger
 JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_integer)
 {
-    return Value(vm.argument(0).is_integral_number());
+    auto number = vm.argument(0);
+
+    // 1. Return IsIntegralNumber(number).
+    return Value(number.is_integral_number());
 }
 
 // 21.1.2.4 Number.isNaN ( number ), https://tc39.es/ecma262/#sec-number.isnan
 JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_nan)
 {
-    return Value(vm.argument(0).is_nan());
+    auto number = vm.argument(0);
+
+    // 1. If number is not a Number, return false.
+    // 2. If number is NaN, return true.
+    // 3. Otherwise, return false.
+    return Value(number.is_nan());
 }
 
 // 21.1.2.5 Number.isSafeInteger ( number ), https://tc39.es/ecma262/#sec-number.issafeinteger
 JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_safe_integer)
 {
-    if (!vm.argument(0).is_number())
-        return Value(false);
-    if (!vm.argument(0).is_integral_number())
-        return Value(false);
-    auto value = vm.argument(0).as_double();
-    return Value(value >= MIN_SAFE_INTEGER_VALUE && value <= MAX_SAFE_INTEGER_VALUE);
+    auto number = vm.argument(0);
+
+    // 1. If IsIntegralNumber(number) is true, then
+    if (number.is_integral_number()) {
+        // a. If abs(ℝ(number)) ≤ 2^53 - 1, return true.
+        if (fabs(number.as_double()) <= MAX_SAFE_INTEGER_VALUE)
+            return Value(true);
+    }
+
+    // 2. Return false.
+    return Value(false);
 }
 
 }