instanceof (custom types or custom built in types) vs typeof (built in types)

instanceof vs typeof

Use instanceof for custom types:
```
var ClassFirst = function () {};
var ClassSecond = function () {};
var instance = new ClassFirst();
typeof instance; // object
typeof instance == 'ClassFirst'; // false
instance instanceof Object; // true
instance instanceof ClassFirst; // true
instance instanceof ClassSecond; // false 
```

Use typeof for simple built in types:
```
'example string' instanceof String; // false
typeof 'example string' == 'string'; // true

'example string' instanceof Object; // false
typeof 'example string' == 'object'; // false

true instanceof Boolean; // false
typeof true == 'boolean'; // true

99.99 instanceof Number; // false
typeof 99.99 == 'number'; // true

function() {} instanceof Function; // true
typeof function() {} == 'function'; // true
```

Use instanceof for complex built in types:

```
/regularexpression/ instanceof RegExp; // true
typeof /regularexpression/; // object

[] instanceof Array; // true
typeof []; //object

{} instanceof Object; // true
typeof {}; // object
And the last one is a little bit tricky:

typeof null; // object
```