Data types Flashcards
What are the seven main data types in JavaScript?
The seven main data types in JavaScript are Undefined, Null, Boolean, Number, BigInt, String, and Symbol.
True or False: In JavaScript, the type of a variable can change during runtime.
True.
What data type is returned when you use the typeof operator on a variable that is not defined?
The typeof operator returns ‘undefined’.
Fill in the blank: The _____ data type represents a sequence of characters.
String.
Which data type can represent whole numbers larger than 2^53 - 1?
BigInt.
What is the result of the expression ‘5’ + 5 in JavaScript?
‘55’ (string concatenation).
True or False: Null is a type of object in JavaScript.
True.
What method can be used to convert a string to a number in JavaScript?
The Number() function or parseInt()/parseFloat() methods.
What will the expression Boolean(0) return?
False.
Which operator is used for strict equality comparison in JavaScript?
The === operator.
Fill in the blank: The _____ function can be used to convert a value to a string.
String.
What type of data does the JSON.stringify() method return?
A string.
What is the default value of an uninitialized variable in JavaScript?
Undefined.
True or False: An array is considered a type of object in JavaScript.
True.
What is the output of typeof NaN in JavaScript?
Number.
Which data type is used to represent true/false values?
Boolean.
What will the parseInt(‘101’, 2) return?
5 (binary to decimal conversion).
Fill in the blank: The _____ operator converts a value to a boolean based on its truthiness.
Boolean.
What value does null equal when compared with == operator?
Null (null == null is true).
How do you check if a variable is of type ‘string’?
Using the typeof operator: typeof variable === ‘string’.
