stringsOnlyObject does typechecking before coercion to string

Video.js

@@ -23,6 +23,29 @@ export default class Video extends Component {
   setNativeProps(nativeProps) {
     this._root.setNativeProps(nativeProps);
   }
+  
+  toTypeString(x) {
+    switch (typeof x) {
+      case "object":
+        return x instanceof Date 
+          ? x.toISOString() 
+          : JSON.stringify(x); // object, null
+      case "undefined":
+        return "";
+      default: // boolean, number, string
+        return x.toString();      
+    }
+  }
+
+  stringsOnlyObject(obj) {
+    const strObj = {};
+
+    Object.keys(obj).forEach(x => {
+      strObj[x] = this.toTypeString(obj[x]);
+    });
+
+    return strObj;
+  }
 
   stringsOnlyObject(obj) {
     const strObj = {};