add a util to check if a polyglot value is javascript undefined

Author: imakira

src/net/coruscation/js4clj/api/converting.clj

@@ -76,3 +76,12 @@
         ;; polyglot time, date, time zone, instant, duration
         :else
         value))
+
+(defn js-undefined-raw?
+  "Check if an value is an instance of `org.graalvm.polyglot.Value` and of JavaScript `undefined` value"
+  [value]
+  (and (instance? org.graalvm.polyglot.Value value)
+       (= (some-> value
+                  (.getMetaObject)
+                  (.getMetaQualifiedName))
+          "undefined")))

test/net/coruscation/js4clj/api/converting_test.clj

@@ -0,0 +1,20 @@
+(ns net.coruscation.js4clj.api.converting-test
+  (:require
+   [clojure.test :refer [deftest is use-fixtures]]
+   [net.coruscation.js4clj.api.converting :as subject]
+   [net.coruscation.js4clj.context :as context]
+   [net.coruscation.js4clj.test-utils :refer [fresh-context]]))
+
+(deftest js-undefined-raw?-test
+  (is (true?
+       (subject/js-undefined-raw?
+        (.eval @context/*context* "js" "undefined"))))
+  (is (false?
+       (subject/js-undefined-raw?
+        (.eval @context/*context* "js" "null"))))
+  (is (false?
+       (subject/js-undefined-raw?
+        (.eval @context/*context* "js" "[]")))))
+
+(use-fixtures :each #'fresh-context)
+