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JavaScript Notes: Operators
Question 1. Explain arithmetic and assignment operators in JavaScript.
Assignment operator assigns a value to left operand from right operand. The equal (=), assigns the value of its right operand to its left operand. In example x = y assigns the value of y will be assigned to x.
There are compound assignment operators which are explained below.
Name | Operator | Meaning |
Assignment | X=Y | X=Y |
Addition assignment | x += y | x = x+ y |
Subtraction assignment | x - = y | x = x - y |
Multiplication assignment | x * = y | x = x * y |
Division assignment | x / = y | x = x / y |
Remainder assignment | x %= y | x = x % y |
Exponentiation assignment | x **= y | x = x ** y |
Left shift assignment | x <<= y | x = x << y |
Right shift assignment | x >>= y | x = x >> y |
Bitwise AND assignment | x & = y | x = x & y |
Bitwise OR assignment | x |= y | x = x | y |
Bitwise XOR assignment | x ^= y | x = x ^ y |
Logical AND assignment | x && = y | x && (x = y) |
Logical OR assignment | x ||= y | x || (x = y) |
Arithmetic operators:
An arithmetic operator accepts numerical values as their operands and returns a single numerical value. The arithmetic operators are addition (+), subtraction (-), multiplication (*), and division (/). In addition to the standard arithmetic operations (+, -, *, /), JavaScript provides the arithmetic operators listed below.
Operator | Description | Example |
Remainder(%) | Binary operator. Returns the integer remainder of dividing the two operands. | 12 % 5 returns 2. |
Increament (++) | Unary operator. Adds one to its operand. If used as a prefix i. e. ++x, returns the value of its operand after adding one; if used as a postfix x++ returns the value of its operand before adding one. | If x is 4, then ++x sets x to 5 and returns 5, whereas x++ returns 4 and, only then, sets x to 5. |
Decreament(--) | Unary operator. Subtracts one from its operand. The return value will act in similar way to increment operator. | If x is 4, then --x sets x to 3 and returns 3, whereas x-- returns 4 and, only then, sets x to 3. |
Unary negation(-) | Unary operator. Returns the negation of its operand. | If x is 3, then -x returns -3 |
Unary plus(+) | Unary operator. Attempts to convert the operand to a number, if it is not already. | +"3" returns 3. +true returns 1. |
Exponentiation Operator (**) | Calculates the base to the exponent power, that is, base**exponent | 2 ** 3 returns 8. 10 ** -1 returns 0.1. |
Question 2. What is the difference between == and ===?
== | === |
Double equals (==) is equality comparison | Triple equals (===) are strict equality comparison |
operator, which transforms the operands to the same type before comparison. | operator, which returns false if there are different types and different content. |
4 == 4 // true | 4 === 4 // true |
"4" == 4 //true | "4" === 4 //true |
4 == "4" // true | 4 === "4" // true |
0 == false // true | var v2 = {"value": "key" }; v1 === v2 //false |
Question 3. Explain comparison and logical operators in JavaScript.
1) Comparison operators — operators that compare values and return true or false. The operators include:
Less than (<) — returns true if the value on the left is less than the value on the right, otherwise it returns false.
Greater than (>) — returns true if the value on the left is greater than the value on the right, otherwise it returns false.
Less than or equal to (<=) — returns true if the value on the left is less than or equal to the value on the right, otherwise it returns false.
Greater than or equal to (>=) — returns true if the value on the left is greater than or equal to the value on the right, otherwise it returns false.
Equal to (===) — returns true if the value on the left is equal to the value on the right, otherwise it returns false.
Not equal to (!==) — returns true if the value on the left is not equal to the value on the right, otherwise it returns false.
2) Logical(Boolean) operators — operators that combine multiple boolean expressions or values and provide a single boolean output. The operators include:
&& (and) — This operator will be truth (act like true) if and only if the expressions on both sides of it are true.
|| (or) — This operator will be truth if the expression on either side of it is true. Otherwise, it will be false (act like false).
! (not) _this returns opposite of the input.
Question 4. Write a note on Bitwise Operators in JavaScript.
Bitwise operators treat its operands as a group of 32-bit binary digits and perform actions. But, the result is shown as a decimal value.
Bitwise AND:
Bitwise AND & returns 1 if both operands are 1 else it returns 0.
Bitwise OR:
Bitwise OR | returns 1 if either of the corresponding bits of one operand is 1 else returns 0.
Bitwise XOR:
Bitwise XOR ^ returns 1 if the corresponding bits are different and returns 0 if the corresponding bits are the same.
Bitwise NOT:
Bitwise NOT ~ inverts the bit( 0 becomes 1, 1 becomes 0).
Bitwise SHIFT operators:
LEFT SHIFT <<: I.e. shifts the elements to the left and insert 0 in the gap formed. For example, 15<<1 or 1111<<1 implies 1110 or 14.
RIGHT SHIFT >>>: It is just the reverse of LEFT SHIFT, that is 15>>>1 or 1111>>>1 implies 0111 or 7.
SIGNED RIGHT SHIFT >>: i.e. it returns the signed right shift. For example, 1111>>1 or 0111 or 7. Since the fourth bit is 0, positive.
Question 5. Write a note on string operators used in JavaScript.
The + operator, += operator used to concatenate strings.
Given that text1 = "Good ", text2 = "day", and text3 = text1 + text2 then text3=goodday.
Question 6. Explain the use of 'let' keyword in JavaScript.
Nan function :
Definition and Usage
The isNaN() function checks whether a value is a valid number
This function returns true if the value equal to Nan result . Otherwise it returns false.
This function is different from the.isNaN() method.
The global isNaN() function, converts the tested value to a Number, once conversion is done then tests it.
Example:
isNaN(123) //false
isNaN(-1.23) //false
isNaN(5-2) //false
isNaN(0) //false
isNaN('123') //false
isNaN('Hello') //true
isNaN('2005/12/12') //true
isNaN('') //false
isNaN(true) //false
isNaN(undefined) //true
isNaN('NaN') //true
isNaN(NaN) //true
isNaN(0 / 0) //true
isNaN(null) //false
Infinity function :
Division by 0 gives you another special value:
> 3/0
Infinity
You can’t perform any operation on positive and negative infinity against each other:
> Infinity - Infinity
NaN
It is still infinity:
> Infinity + Infinity
Infinity
> 5 * Infinity
Infinity
Question 7. Is there any ternary operator in JavaScript?
Yes, ‘?’ is the ternary operator. It is same as in C. That is, (condition? true: false).
For example, (12>2?1:0) returns 1.
Question 8. Explain the use of 'typeof' operator.
The uses of typeof operator are listed below:
Type of can be used to check whether a variable exists and it has a value.
The typeof operator used for checking that a value is neither undefined nor null.
It differentiate between objects and primitives.
It tells What is the type of a primitive value.
typeof check whether a value is a function.
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