Javascript interview questions (comments are original)

I. multiple choice questions

1. Which of the following statements will generate a running error? ()

A. var OBJ = ();

B. var OBJ = [];

C. var OBJ = {};

D. var OBJ = //;

Comments: OBJ = [] defines an array object, OBJ = {} defines an object literal, OBJ = // defines

JavaScript does not write var OBJ = () as a regular object!

2. Select the true expression for the result: (c)

A. null instanceof
Object

B. null =
Undefined

C. null =
Undefined

D. Nan = Nan

Evaluation: Option D returns false because Nan is not equal to any value, including itself (remember that the data type undefined is equal to null )!