JavaScript Variables, data types, and operators MCQs

JavaScript variables are used to store and manage data.

In modern JavaScript, you can use the let keyword to declare variables.

let allows reassignment, while const does not. const creates a constant value.

The value of a variable that is declared but not initialized is undefined.

The Number data type is used to represent both whole numbers and floating-point numbers.

JavaScript performs type coercion and converts the number to a string before concatenation.

The typeof operator is used to determine the data type of a value.

The '==' operator checks for equality without considering data types (type coercion).

The '===' operator checks for equality while also considering data types (no type coercion).

The '&&' operator performs a logical AND operation.

The '++' operator is used to increment a variable by 1.

The typeof operator is used to check the data type of a value.

The '!' operator negates a Boolean value, turning true into false and vice versa.

JavaScript follows the order of operations, so multiplication is done before addition.

Multi-line comments in JavaScript are enclosed in '/* */'.

The % operator calculates the remainder, so 5 % 2 is 1.

The + operator is used to concatenate strings in JavaScript.

NaN is a special value representing "Not-a-Number."

JavaScript performs type coercion, so 5 is considered equal to '5'.

You declare a constant variable in JavaScript using the const keyword.

Math.random() is used to generate random numbers between 0 and 1.

null represents a missing or non-existent value in JavaScript.

JavaScript performs type coercion, converting the string to a number for subtraction.

The '||' operator is used to perform a logical OR operation.

The typeof operator is used to determine the data type of a value.

JavaScript performs string concatenation when one of the operands is a string.

The parseInt() function is used to convert a string to an integer.

The operator is used for exponentiation in JavaScript.

The concat() method is used to concatenate arrays in JavaScript.

The typeof operator returns 'object' for null values, which is a historical quirk in JavaScript.

The .length property returns the length of a string, which is 5 in this case.

The Date object represents date and time in JavaScript.

The '&&' operator returns true if both conditions are true.

The '===' operator checks for equality and data type, so a string is not equal to a number.

NaN is not equal to itself in JavaScript.

The . operator is used to access object properties.

Division by zero results in positive or negative infinity in JavaScript.

The '=' operator is used for assignment in JavaScript.

null and undefined are loosely equal in JavaScript.

The '%' operator is used to calculate the remainder of a division operation.

Math.floor() returns the largest integer less than or equal to a given number.

JavaScript converts the strings to numbers and performs subtraction.

The '!' operator is used for the logical NOT operation.

The '&&' operator returns false if any operand is false.

JavaScript converts the string to a number and performs multiplication.

The '!=' operator checks for inequality without considering data types (type coercion).

JavaScript converts the boolean true to a string and concatenates it.

null is converted to 0 in arithmetic operations.

The toFixed() function rounds a number to a specified number of decimal places and returns a string.

The '%' operator is used for calculating the remainder of a division operation in JavaScript.

JavaScript converts the string to a number and performs multiplication.

The isNaN() function checks if a value is not a number.

JavaScript performs type coercion, and both '5' and true are considered "truthy."

In a browser environment, the Window object represents the global context.

Math.ceil() rounds a number up to the nearest integer.

The '||' operator is used for the logical OR operation.

null is converted to 0 in arithmetic operations.

The <= operator checks if a value is less than or equal to another value.

The '||' operator returns true if either operand is true.

JavaScript converts the string to a number and performs subtraction.

Math.sqrt() calculates the square root of a number.

The > operator checks if a value is greater than another value.

The && operator returns true if both operands are true.

JavaScript converts null to a string and concatenates it.

The '^' operator is used for the logical XOR (exclusive or) operation.

JavaScript concatenates strings when both operands are strings.

The toUpperCase() function converts a string to uppercase.

The '!==' operator checks for inequality while also considering data types.

Division by a non-numeric string results in NaN.

The '==' operator checks for equality without considering data types (type coercion).

JavaScript cannot convert the string 'two' to a number.

The '[]' operator is used to access array elements by index.

Adding a number to undefined results in NaN.

Math.round() rounds a number to the nearest integer.

The '||' operator returns true if at least one operand is true.

The '&&' operator returns false if one operand is false.

The '&' operator is used for bitwise AND in JavaScript.

JavaScript cannot convert the strings to numbers.

JavaScript performs type coercion, so 5 is considered equal to '5'.

The '|' operator is used for bitwise OR in JavaScript.

Math.abs() returns the absolute value of a number.

JavaScript compares strings based on their Unicode values.

The << operator performs a bitwise shift to the left.

The '===' operator checks for equality and data type, so a string is not equal to a boolean.

Math.max() returns the maximum value from a list of numbers.

The '^' operator is used for the bitwise XOR operation.

The '&&' operator returns true if both operands are true.

The '!=' operator checks for inequality without considering data types.

The toString() function converts a number to a string.

The '&&' operator returns false if any operand is false.

The '~' operator is used for the bitwise NOT operation.

The '||' operator returns true if at least one operand is true.

Math.min() returns the minimum value from a list of numbers.

The >= operator checks if a value is greater than or equal to another value.

The >> operator performs a bitwise shift to the right with sign extension.

JavaScript performs type coercion and considers the strings as numbers for comparison.

Math.random() is used to generate random numbers between 0 and 1.

JavaScript performs type coercion and considers the strings as numbers for comparison.

The > operator checks if a value is strictly greater than another value.

JavaScript compares strings based on their Unicode values.