From b7acb0785de1076b9f2f764cba9beed5b2763c27 Mon Sep 17 00:00:00 2001
From: Tyler Wilcock <tyler.l.wilcock@gmail.com>
Date: Sat, 21 Jul 2018 15:19:30 -0500
Subject: [PATCH] Add Number.isNaN() binding (#532)

---
 crates/js-sys/src/lib.rs           |  7 +++++++
 crates/js-sys/tests/wasm/Number.rs | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/crates/js-sys/src/lib.rs b/crates/js-sys/src/lib.rs
index ba21a468b..43e2efb21 100644
--- a/crates/js-sys/src/lib.rs
+++ b/crates/js-sys/src/lib.rs
@@ -1263,6 +1263,13 @@ extern "C" {
     #[wasm_bindgen(static_method_of = Number, js_name = isInteger)]
     pub fn is_integer(value: &JsValue) -> bool;
 
+    /// The Number.isNaN() method determines whether the passed value is NaN and its type is Number.
+    /// It is a more robust version of the original, global isNaN().
+    ///
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN
+    #[wasm_bindgen(static_method_of = Number, js_name = isNaN)]
+    pub fn is_nan(value: &JsValue) -> bool;
+
     /// The Number.isSafeInteger() method determines whether the provided value is a number
     /// that is a safe integer.
     ///
diff --git a/crates/js-sys/tests/wasm/Number.rs b/crates/js-sys/tests/wasm/Number.rs
index fdd646092..93e5b0124 100644
--- a/crates/js-sys/tests/wasm/Number.rs
+++ b/crates/js-sys/tests/wasm/Number.rs
@@ -19,6 +19,24 @@ fn is_integer() {
     assert!(!Number::is_integer(&42.1.into()));
 }
 
+#[wasm_bindgen_test]
+fn is_nan() {
+    assert!(Number::is_nan(&NAN.into()));
+
+    assert!(!Number::is_nan(&JsValue::TRUE));
+    assert!(!Number::is_nan(&JsValue::NULL));
+    assert!(!Number::is_nan(&37.into()));
+    assert!(!Number::is_nan(&"37".into()));
+    assert!(!Number::is_nan(&"37.37".into()));
+    assert!(!Number::is_nan(&"".into()));
+    assert!(!Number::is_nan(&" ".into()));
+
+    // These would all return true with the global isNaN()
+    assert!(!Number::is_nan(&"NaN".into()));
+    assert!(!Number::is_nan(&JsValue::UNDEFINED));
+    assert!(!Number::is_nan(&"blabla".into()));
+}
+
 #[wasm_bindgen_test]
 fn is_safe_integer() {
     assert_eq!(Number::is_safe_integer(&42.into()), true);