Which code segment should you use?

You are developing an application that uses a third-party JavaScript library named doWork().

The library occasionally throws an "object is null or undefined" error with an error code of-2146823281.

The application must:

• Extract and handle the exceptions thrown by doWork()

• Continue normal program execution if other exceptions occur

You need to implement the requirements.

Which code segment should you use?

A . Option A
B . Option B
C . Option C
D . Option D

View Answer

Answer: C

Explanation:

* The try statement lets you test a block of code for errors.

The catch statement lets you handle the error.

The JavaScript statements try and catch come in pairs:

try {

Block of code to try

}

catch(err) {

Block of code to handle errors

}

* object.number [= errorNumber]

Returns or sets the numeric value associated with a specific error. The Error object’s default property is number.

* Example:

The following example causes an exception to be thrown and displays the error code that is derived from the error number.

try

{

// Cause an error.

var x = y;

}

catch(e)

{

document.write ("Error Code: ");

document.write (e.number & 0xFFFF)

document.write ("<br />");

document.write ("Facility Code: ")

document.write(e.number>>16 & 0x1FFF)

document.write ("<br />");

document.write ("Error Message: ")

document.write (e.message)

}

The output of this code is as follows.

Error Code: 5009

Facility Code: 10

Error Message: ‘y’ is undefined

Reference: JavaScript Errors – Throw and Try to Catch; number Property (Error) (JavaScript)