Add is_truthy, is_falsy

Author: ThomasdenH

crates/cli-support/src/intrinsic.rs

@@ -85,6 +85,12 @@ intrinsics! {
         #[symbol = "__wbindgen_is_string"]
         #[signature = fn(ref_anyref()) -> Boolean]
         IsString,
+        #[symbol = "__wbindgen_is_truthy"]
+        #[signature = fn(ref_anyref()) -> Boolean]
+        IsTruthy,
+        #[symbol = "__wbindgen_is_falsy"]
+        #[signature = fn(ref_anyref()) -> Boolean]
+        IsFalsy,
         #[symbol = "__wbindgen_object_clone_ref"]
         #[signature = fn(ref_anyref()) -> Anyref]
         ObjectCloneRef,

crates/cli-support/src/js/mod.rs

@@ -2299,6 +2299,16 @@ impl<'a> Context<'a> {
                 format!("typeof({}) === 'string'", args[0])
             }
 
+            Intrinsic::IsTruthy => {
+                assert_eq!(args.len(), 1);
+                format!("!!{}", args[0])
+            }
+
+            Intrinsic::IsFalsy => {
+                assert_eq!(args.len(), 1);
+                format!("!{}", args[0])
+            }
+
             Intrinsic::ObjectCloneRef => {
                 assert_eq!(args.len(), 1);
                 args[0].clone()

src/lib.rs

@@ -332,6 +332,22 @@ impl JsValue {
         unsafe { __wbindgen_is_function(self.idx) == 1 }
     }
 
+    /// Tests whether the value is ["truthy"].
+    /// 
+    /// ["truthy"]: https://developer.mozilla.org/en-US/docs/Glossary/Truthy
+    #[inline]
+    pub fn is_truthy(&self) -> bool {
+        unsafe { __wbindgen_is_truthy(self.idx) == 1 }
+    }
+
+    /// Tests whether the value is ["falsy"].
+    /// 
+    /// ["falsy"]: https://developer.mozilla.org/en-US/docs/Glossary/Falsy
+    #[inline]
+    pub fn is_falsy(&self) -> bool {
+        unsafe { __wbindgen_is_falsy(self.idx) == 1 }
+    }
+
     /// Get a string representation of the JavaScript object for debugging
     #[cfg(feature = "std")]
     fn as_debug_string(&self) -> String {
@@ -502,6 +518,8 @@ externs! {
         fn __wbindgen_is_object(idx: u32) -> u32;
         fn __wbindgen_is_function(idx: u32) -> u32;
         fn __wbindgen_is_string(idx: u32) -> u32;
+        fn __wbindgen_is_truthy(idx: u32) -> u32;
+        fn __wbindgen_is_falsy(idx: u32) -> u32;
 
         fn __wbindgen_number_get(idx: u32, invalid: *mut u8) -> f64;
         fn __wbindgen_boolean_get(idx: u32) -> u32;

tests/wasm/truthy_falsy.rs

@@ -0,0 +1,25 @@
+#[wasm_bindgen_test]
+fn test_is_truthy() {
+    assert_eq!(JsValue::from(0).is_truthy(), false);
+    assert_eq!(JsValue::from("".to_string()).is_truthy(), false);
+    assert_eq!(JsValue::from(false).is_truthy(), false);
+    assert_eq!(JsValue::NULL.is_truthy(), false);
+    assert_eq!(JsValue::UNDEFINED.is_truthy(), false);
+
+    assert_eq!(JsValue::from(10).is_truthy(), true);
+    assert_eq!(JsValue::from("null".to_string()).is_truthy(), true);
+    assert_eq!(JsValue::from(true).is_truthy(), true);
+}
+
+#[wasm_bindgen_test]
+fn test_is_falsy() {
+    assert_eq!(JsValue::from(0).is_falsy(), true);
+    assert_eq!(JsValue::from("".to_string()).is_falsy(), true);
+    assert_eq!(JsValue::from(false).is_falsy(), true);
+    assert_eq!(JsValue::NULL.is_falsy(), true);
+    assert_eq!(JsValue::UNDEFINED.is_falsy(), true);
+
+    assert_eq!(JsValue::from(10).is_falsy(), false);
+    assert_eq!(JsValue::from("null".to_string()).is_falsy(), false);
+    assert_eq!(JsValue::from(true).is_falsy(), false);
+}