add promise queue

1-js/04-object-basics/03-symbol/article.md

@@ -18,7 +18,7 @@ let id = Symbol();
 
 We can also give symbol a description (also called a symbol name), mostly useful for debugging purposes:
 
-```js
+```js run
 // id is a symbol with the description "id"
 let id = Symbol("id");
 ```
@@ -50,6 +50,8 @@ alert(id); // TypeError: Cannot convert a Symbol value to a string
 */!*
 ```
 
+That's a "language guard" against messing up, because strings and symbols are fundamentally different and should not occasionally convert one into another.
+
 If we really want to show a symbol, we need to call `.toString()` on it, like here:
 ```js run
 let id = Symbol("id");
@@ -58,7 +60,14 @@ alert(id.toString()); // Symbol(id), now it works
 */!*
 ```
 
-That's a "language guard" against messing up, because strings and symbols are fundamentally different and should not occasionally convert one into another.
+Or get `symbol.description` property to get the description only:
+```js run
+let id = Symbol("id");
+*!*
+alert(id.description); // id
+*/!*
+```
+
 ````
 
 ## "Hidden" properties