Fix a typo and the placement of a comma

Author: BonsaiDen

doc/typeof.md

@@ -74,7 +74,7 @@ referencing it would result in a `ReferenceError`. This is the only thing
 In order to check the type of an object, it is highly recommended to use 
 `Object.prototype.toString`; as this is the only reliable way of doing so. 
 As shown in the above type table, some return values of `typeof` are not defined 
-in the specification; thus, the can across various implementations.
+in the specification; thus, they can differ across various implementations.
 
 Unless checking whether a variable is defined, `typeof` should be avoided at
 **all costs**.

doc/undefined.md

@@ -29,8 +29,8 @@ value does not change the value of the **type** `undefined`.
 Still, in order to compare something against the value of `undefined` it is
 necessary to retrieve the value of `undefined` in the first place.
 
-In order to protect code against a possible overwritten `undefined` variable a 
-, common technique used is to add an additional parameter to the encapsulation
+In order to protect code against a possible overwritten `undefined` variable, a 
+common technique used is to add an additional parameter to the encapsulation
 [anonymous wrapper](#scopes), which gets no argument passed to it.
 
     var undefined = 123;