Operators

We need operators when performing any operation in a programming language. JavaScript also has arithmetic, assignment, comparison, logical, bitwise, and unary operators, among others. Let's take a look at these:

var num = 0; // {1}  
num = num + 2; 
num = num * 3;  
num = num / 2;  
num++; 
num--; 
 
num += 1; // {2} 
num -= 2; 
num *= 3; 
num /= 2; 
num %= 3; 
 
console.log('num == 1 : ' + (num == 1)); // {3}  
console.log('num === 1 : ' + (num === 1));  
console.log('num != 1 : ' + (num != 1));  
console.log('num > 1 : ' + (num > 1)); 
console.log('num < 1 : ' + (num < 1));  
console.log('num >= 1 : ' + (num >= 1));  
console.log('num <= 1 : ' + (num <= 1)); 
 
console.log('true && false : ' + (true && false)); // {4}  
console.log('true || false : ' + (true || false));  
console.log('!true : ' + (!true)); 

In line {1}, we have the arithmetic operators. In the following table, we have the operators and their descriptions:

Arithmetic operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus (remainder of a division operation)
++	Increment
--	Decrement

 

In line {2}, we have the assignment operators. In the following table, we have the operators and their descriptions:

Assignment operator	Description
=	Assignment
+=	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)

 

In line {3}, we have the comparison operators. In the following table, we have the operators and their descriptions:

Comparison operator	Description
==	Equal to
===	Equal to (both value and object type)
!=	Not equal to
>	Greater than
>=	Greater than or equal to
<	Less than
<=	Less than or equal to

 

Finally, in line {4}, we have the logical operators. In the following table, we have the operators and their descriptions:

Logical operator	Description
&&	And
||	Or
!	Not

 

JavaScript also supports bitwise operators, which are shown as follows:

console.log('5 & 1:', (5 & 1)); 
console.log('5 | 1:', (5 | 1)); 
console.log('~ 5:', (~5)); 
console.log('5 ^ 1:', (5 ^ 1)); 
console.log('5 << 1:', (5 << 1)); 
console.log('5 >> 1:', (5 >> 1)); 

The following table contains a more detailed description of the bitwise operators:

Bitwise operator	Description
&	And
|	Or
~	Not
^	Xor
<<	Left shift
>>	Right shift

 

The typeof operator returns the type of the variable or expression. For example, have a look at the following code:

console.log('typeof num:', typeof num); 
console.log('typeof Packt:', typeof 'Packt'); 
console.log('typeof true:', typeof true); 
console.log('typeof [1,2,3]:', typeof [1,2,3]); 
console.log('typeof {name:John}:', typeof {name:'John'}); 

The output will be as follows:

    typeof num: number
    typeof Packt: string
    typeof true: boolean
    typeof [1,2,3]: object
    typeof {name:John}: object
 

According to the specification, there are two data types in JavaScript:

• Primitive data types: Null, undefined, string, number, boolean, and symbol
• Derived data types/objects: JavaScript objects, including functions, arrays, and regular expressions 

JavaScript also supports the delete operator, which deletes a property from an object:

var myObj = {name: 'John', age: 21}; 
delete myObj.age; 
console.log(myObj); //outputs Object {name: "John"} 

In this book's algorithms, we will be using some of these operators.