You are developing an application that uses a JavaScript library. The library contains the following functions.
The application uses the following code. (Line numbers are included for reference only.)
The library may throw many types of exceptions. The exceptions are grouped by category.
You need to catch and identify the exceptions by group.
Which code segment should you insert at line 05?
A.
Option A
B.
Option B
C.
Option C
D.
Option D
Explanation:
instanceof
The instanceof operator tests whether an object has in its prototype chain the prototype property of a
constructor.
The instanceof operator tests presence of constructor.prototype in object prototype chain.
Example::
// defining constructorsfunction C(){}
function D(){}
var o = new C();
// true, because: Object.getPrototypeOf(o) === C.prototype
o instanceof C;
// false, because D.prototype is nowhere in o’s prototype chain
o instanceof D;
instanceof
just to clarify:
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
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