Q
What is the result of the expression typeof undefinedVariable if undefinedVariable is not declared?

Answer & Solution

Answer: Option C
Solution:
When attempting to access a variable that has not been declared, JavaScript returns 'undefined' as the result of the expression 'typeof undefinedVariable'.
Related Questions on Average

Which of the following statements is true regarding the behavior of 'Undefined' and 'Null' in JavaScript?

A). Undefined and Null are both falsy values in JavaScript.

B). Undefined and Null are both truthy values in JavaScript.

C). Undefined and Null have the same data type in JavaScript.

D). Undefined and Null cannot be compared in JavaScript.

When does a variable typically have an 'Undefined' value?

A). When it is intentionally set to represent no value.

B). When it is assigned a default value.

C). When it is declared but not initialized.

D). When it is explicitly set to 'Undefined'.

How do you assign a variable to have a value of 'Null'?

A). Using the assignment operator =.

B). Using the null keyword.

C). Using the undefined keyword.

D). Using the void operator.

Which statement is true regarding the use of 'Undefined'?

A). Undefined is commonly used to reset variables in loops.

B). Undefined is generally avoided and considered a programming error.

C). Undefined is used to represent empty strings.

D). Undefined is only used in function declarations.

Which of the following is a valid use case for 'Null' in JavaScript?

A). Storing default values in variables.

B). Clearing or resetting object references.

C). Assigning placeholders in arrays.

D). Checking if a variable exists.

What does the expression typeof null return in JavaScript?

A). null

B). object

C). undefined

D). function

How does the typeof operator behave when applied to an 'Undefined' value?

A). It returns 'undefined'.

B). It returns 'null'.

C). It throws an error.

D). It returns 'object'.

Which of the following scenarios is a common cause of variables having an 'Undefined' value?

A). When variables are explicitly set to 'Undefined'.

B). When variables are declared but not initialized.

C). When variables are intentionally set to 'Null'.

D). When variables are assigned default values.

How do you check if a variable has an 'Undefined' value in JavaScript?

A). Using the undefined keyword.

B). Using the null keyword.

C). Using the typeof operator.

D). Using the empty keyword.

What is the purpose of using 'Null' over 'Undefined' in certain programming scenarios?

A). To represent an intentional absence of value or object reference.

B). To assign default values to variables.

C). To represent uninitialized variables.

D). To check for variable existence.