Copy edits (#35536)

* Copy edits to Basic JavaScript section

* Copy edits to ES6 section

* Update index.md

guide/english/certifications/javascript-algorithms-and-data-structures/es6/prevent-object-mutation/index.md

@@ -31,7 +31,7 @@ _You need to freeze the `MATH_CONSTANTS` object so that no one is able to alter
       
       try {
         MATH_CONSTANTS.PI = 99;
-      } catch( ex ) {
+      } catch(ex) {
         console.log(ex);
       }
       return MATH_CONSTANTS.PI;