JavaScript operators: definition, types, and examples

The utilization of operators is one of the fundamental building blocks that JavaScript consists of. Operators are used to perform a wide range of operations in JavaScript, including arithmetic, logical, assignment, and comparison. Operators are crucial to the operation of any JavaScript program because they carry out tasks that can range from as simple as adding numbers together to as complex as performing intricate logical operations.

In this article, we'll go in-depth on the various JavaScript operators and show you how you can use them to manipulate data and carry out intricate operations. So fasten your seatbelts and get ready to explore JavaScript's operator world!

Types of operators in JavaScript

These are the following types of operators available in JavaScript:

Arithmetic operators are used when we need to perform arithmetical tasks.
Assignment operators are used to assign values.
Comparison operators are used to compare between two variables or values.
Logical (relational) operators are used to connect multiple expressions to evaluate and return a boolean value (true or false).
Bitwise operators are used to perform bitwise (or bit-wise or bit-by-bit) operations.
The ?: (ternary or conditional operator) is used as an alternative to if-else.

Arithmetic operators in JavaScript

Arithmetic operators in JavaScript are used when we need to perform arithmetical tasks. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>

  <p>10 + 20 = <span id="mySpan"></span></p>
   
   <script>
      let x = 10, y = 20;
      document.getElementById("mySpan").innerHTML = x+y;
   </script>
   
</body>
</html>

Output

10 + 20 =

List of all arithmetic operators in JavaScript

Addition (+)
Subtraction (-)
Multiplication (*)
Exponentiation (**)
Division (/)
Modulus (%)
Increment (++)
Decrement (--)

JavaScript arithmetic operators example

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p id="1"></p>
   <p id="2"></p>
   <p id="3"></p>
   <p id="4"></p>
   <p id="5"></p>
   <p id="6"></p>
   <p id="7"></p>
   <p id="8"></p>
   
   <script>
      let a = 20, b = 10, c = 3, d = 4;

      res = a+b;
      document.getElementById("1").innerHTML = res;
      
      res = a-b;
      document.getElementById("2").innerHTML = res;
      
      res = a*b;
      document.getElementById("3").innerHTML = res;
      
      res = c**d;
      document.getElementById("4").innerHTML = res;
      
      res = a/b;
      document.getElementById("5").innerHTML = res;
      
      res = a%c;
      document.getElementById("6").innerHTML = res;
      
      res = a++;
      document.getElementById("7").innerHTML = res;
      
      res = a--;
      document.getElementById("8").innerHTML = res;
   </script>
   
</body>
</html>

Output

The increment (++) and decrement (--) operators in JavaScript

Both increment and decrement operators in JavaScript are of two types, namely:

Pre-increment operator (++x)
Post-increment operator (x++)
Pre-decrement operator (--x)
Post-decrement operator (x--)

The pre-increment or pre-decrement is used to increment or decrement the value before use. where the post-increment or post-decrement is used to use the value before the increment or decrement. The value will be incremented or decremented by 1 each time. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p id="a"></p> 
   <p id="b"></p> 
   <p id="c"></p> 
   <p id="d"></p> 
   <p id="e"></p> 
   <p id="f"></p> 
   <p id="g"></p> 
   <p id="h"></p> 

   <script>
      let m = 10, n = 20;

      document.getElementById("a").innerHTML = m++;
      document.getElementById("b").innerHTML = m;
      
      document.getElementById("c").innerHTML = ++m;
      document.getElementById("d").innerHTML = m;
        
      document.getElementById("e").innerHTML = n--;
      document.getElementById("f").innerHTML = n;
      
      document.getElementById("g").innerHTML = --n;
      document.getElementById("h").innerHTML = n;
   </script>
   
</body>
</html>

Output

Assignment operators in JavaScript

Assignment operators in JavaScript are used to assign values. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p id="abc"></p>
   <p id="xyz"></p>

   <script>
      let x;

      x = 20;
      document.getElementById("abc").innerHTML = x;
      
      x += 5;
      document.getElementById("xyz").innerHTML = x;
   </script>
   
</body>
</html>

Output

List of all assignment operators in JavaScript

Simple assign (=)
Add, then assign (+=)
Subtract, then assign (-=)
Multiply, then assign (*=)
Divide, then assign (/=)
Modulus, then assign (%=)
Exponent, then assign (**=)

JavaScript assignment operators example

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>

   <p id="para1"></p>
   <p id="para2"></p>
   <p id="para3"></p>
   <p id="para4"></p>
   <p id="para5"></p>
   <p id="para6"></p>
   <p id="para7"></p>
   
   <script>
      let a = 20, b = 3, res;

      res = b;
      document.getElementById("para1").innerHTML = res;
      
      res += 5;
      document.getElementById("para2").innerHTML = res;
      
      res -= 5;
      document.getElementById("para3").innerHTML = res;

      res *= 5;
      document.getElementById("para4").innerHTML = res;
      
      res /= 10;
      document.getElementById("para5").innerHTML = res;
      
      a %= 3;
      document.getElementById("para6").innerHTML = a;
      
      b **= 4;
      document.getElementById("para7").innerHTML = b;
   </script>
   
</body>
</html>

Output

Note: The expression x += 10 is the same as x = x + 10. Alternatively, x += y is equivalent to x = x + y.

Comparison operators in JavaScript

Comparison operators in JavaScript are used to compare between two variables or values. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p id="xyz"></p>

   <script>
      let x = 20;
      let y = 20;
      if(x==y) {
         document.getElementById("xyz").innerHTML = "The value of 'x' is equal to the value of 'y'";
      } else {
         document.getElementById("xyz").innerHTML = "The value of 'x' is not equal to the value of 'y'";
      }
   </script>
   
</body>
</html>

Output

Note: Comparison operators in JavaScript returns boolean values (true or false). Therefore, x==y or 20==20 returns true because both numbers are obviously equal to each other.

List of all comparison operators in JavaScript

Operator	Name
==	equal to
===	equal value and equal type
!=	not equal
!==	not equal value or not equal type
<	less than
>	greater than
<=	less than or equal to
>=	greater than or equal to

JavaScript comparison operators example

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p id="para1"></p>
   <p id="para2"></p>
   <p id="para3"></p>
   <p id="para4"></p>
   <p id="para5"></p>
   <p id="para6"></p>
   <p id="para7"></p>
   <p id="para8"></p>
   <p id="para9"></p>
   <p id="para10"></p>
   <p id="para11"></p>
   <p id="para12"></p>
   <p id="para13"></p>
   <p id="para14"></p>
   <p id="para15"></p>
   <p id="para16"></p>
   <p id="para17"></p>
   <p id="para18"></p>
   
   <script>
      let a = 10, b = 10, c = 20, d = "10";
      
      document.getElementById("para1").innerHTML = a==b;
      document.getElementById("para2").innerHTML = a==c;
      
      document.getElementById("para3").innerHTML = a===b;
      document.getElementById("para4").innerHTML = a===c;
      document.getElementById("para5").innerHTML = a===d;

      document.getElementById("para6").innerHTML = a!=b;
      document.getElementById("para7").innerHTML = a!=c;

      document.getElementById("para8").innerHTML = a!==b;
      document.getElementById("para9").innerHTML = a!==c;
      document.getElementById("para10").innerHTML = a!==d;
      
      document.getElementById("para11").innerHTML = a>b;
      document.getElementById("para12").innerHTML = a>c;

      document.getElementById("para13").innerHTML = a<b;
      document.getElementById("para14").innerHTML = a<c;

      document.getElementById("para15").innerHTML = a>=b;
      document.getElementById("para16").innerHTML = a>=c;

      document.getElementById("para17").innerHTML = a<=b;
      document.getElementById("para18").innerHTML = a<=c;
   </script>
   
</body>
</html>

Output

Logical operators in JavaScript

Logical operators in JavaScript are used to connect multiple expressions to evaluate and return a boolean value (true or false). For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>

   <p>Largest = <span id="xyz"></span></p>
   
   <script>
      var a = 10, b = 20, c = 30, large;
      if(a>b && a>c) {
         large = a;
      }
      else if(b>a && b>c) {
         large = b;
      }
      else {
         large = c;
      }
      document.getElementById("xyz").innerHTML = large;
   </script>
   
</body>
</html>

Output

Largest = 30

List of all logical operators in JavaScript

Logical OR (||)
Logical AND (&&)
Logical NOT (!)

JavaScript logical OR (||) operator

The || operator returns true if any of the expressions evaluate to be true. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>

   <p id="abc"></p>
   
   <script>
      var x = 10, y = 12, z = 11, res;
      res = x>y || y>z;
      document.getElementById("abc").innerHTML = res;
   </script>
   
</body>
</html>

Output

In the above example, since the first expression, which is x>y or 10>12, evaluates to be false but the second expression, which is y>z or 12>11, evaluates to be true, therefore true will be initialized to the res variable.

JavaScript logical AND (&&) operator

The && operator returns true if all the expressions evaluate to be true. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>

   <p id="myPara"></p>
   
   <script>
      var x = 10, y = 12, z = 11, res;
      res = z>x && y>z;
      document.getElementById("myPara").innerHTML = res;
   </script>
   
</body>
</html>

Output

JavaScript logical NOT (!) operator

The ! operator reverses the boolean value. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>

   <p id="mp"></p>
   
   <script>
      var x = 10, y = 12, z = 11, res;
      res = !(z>x && y>z);
      document.getElementById("mp").innerHTML = res;
   </script>
   
</body>
</html>

Output

Bitwise operators in JavaScript

Bitwise operators in JavaScript are used to perform bitwise (bit-wise or bit-by-bit) operations. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p id="xyz"></p>
   
   <script>
      let x = 6, y = 3;
      document.getElementById("xyz").innerHTML = x & y;
   </script>
   
</body>
</html>

Output

Note: Bit operators work on 32-bit numbers. Bitwise operations go on bit patterns (binary numerals) and involve individual bit manipulation.

In the above example, the binary equivalent of 6 is 110 (or 0000 0000 0000 0000 0000 0000 0000 0110 in a 32-bit number). Whereas the binary equivalent of 3 is 11 (or 0000 0000 0000 0000 0000 0000 0000 0011 in a 32-bit number). Therefore:

    1 1 0
&   0 1 1
----------
    0 1 0

The 010 or 10 is equal to 2 in decimal. That is, in 32-bit numbers:

    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 (6)
&   0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 (3)
-----------------------------------------------------------------------
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 (2)

List of all Bitwise operators in JavaScript

Bitwise AND (&)
Bitwise OR (|)
Bitwise XOR (^)
Bitwise NOT (˜)
Bitwise Right Shift (>>)
Bitwise Left Shift (<<)
Bitwise Unsigned Right Shift (>>>)

To learn about Bitwise operators with examples in detail, refer to its separate tutorial.

?: (conditional or ternary) operator in JavaScript

The ?: (conditional or ternary) operator in JavaScript takes three operands and is used as an alternative to if-else. For example:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <script>
      let x = 10, y = 20;
      x>y ? console.log(x) : console.log(y);
   </script>
   
</body>
</html>

The snapshot given below shows the sample output produced by the above JavaScript example:

The same JavaScript code can also be written as:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p>Largest = <span id="xyz"></span></p>
   
   <script>
      let x = 10, y = 20, large;
      large = x>y ? x : y;
      document.getElementById("xyz").innerHTML = large;
   </script>
   
</body>
</html>

Output

Largest = 20

JavaScript Ternary Operator (?:) Syntax

The syntax of the ternary operator in JavaScript is:

condition ? evaluateIfTrue : evaluateIfFalse

That is, if the condition evaluates to be true, then the whole expression is replaced with evaluateIfTrue, otherwise with evaluateIfFalse. For example:

20==20 ? document.write("Both numbers are equal") : document.write("Both numbers are not equal")

Since the condition 20==20 evaluates to be true, therefore the first expression gets executed, that is:

document.write("Both numbers are equal")

will be executed, and Both numbers are equal will be displayed on the output.

Nested ternary operator in JavaScript

To understand the nested ternary operator in JavaScript, the best and most simple example that I can give you is finding the largest of three numbers using the ternary operator:

HTML with JavaScript Code

<!DOCTYPE html>
<html>
<body>
   
   <p>Largest = <span id="abc"></span></p>
   
   <script>
      let a = 10, b = 20, c = 30, large;
      large = (a>b) ? ((b>c) ? (a) : (c>a ? c : a)) : (b>c ? b : c);
      document.getElementById("abc").innerHTML = large;
   </script>
   
</body>
</html>

Output

Largest =

In above example, the following expression:

(a>b) ? ((b>c) ? (a) : (c>a ? c : a)) : (b>c ? b : c);

will be evaluated in a way that:

First, the condition (a>b) gets evaluated.
Since the condition (a>b) or (10>20) evaluates to be false.
Therefore, (b>c ? b : c) replaced the whole expression.
Now the condition b>c gets evaluated.
Since the condition b>c or 20>30 evaluates to be false.
Therefore, c replaced the whole expression.
Since the value of c is 30, 30 gets initialized as a large variable.

The operators not covered in this post are "typeof" and "instanceof." The "typeof" operator is used to determine the type of a variable, while the "instanceof" operator is used to determine whether the prototype property of a constructor appears in an object's prototype chain.

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