JavaScript Operators
Example
Assign values to variables and add them together:
var y = 2; // assign the value 2 to y
var z = x + y; // assign the value 7 to z (x + y)
JavaScript Arithmetic Operators
Arithmetic operators are used to perform arithmetic on numbers (literals or variables).
Operator | Description |
---|---|
+ | Addition |
- | Subtraction |
* | Multiplication |
/ | Division |
% | Modulus |
++ | Increment |
-- | Decrement |
The addition operator (+) adds numbers:
The multiplication operator (*) multiplies numbers.
You will learn more about JavaScript operators in the next chapters.
JavaScript Assignment Operators
Assignment operators assign values to JavaScript variables.
Operator | Example | Same As |
---|---|---|
= | x = y | x = y |
+= | x += y | x = x + y |
-= | x -= y | x = x - y |
*= | x *= y | x = x * y |
/= | x /= y | x = x / y |
%= | x %= y | x = x % y |
The assignment operator (=) assigns a value to a variable.
The addition assignment operator (+=) adds a value to a variable.
JavaScript String Operators
The + operator can also be used to add (concatenate) strings.
When used on strings, the + operator is called the concatenation operator.
Example
txt2 = "Doe";
txt3 = txt1 + " " + txt2;
The result of txt3 will be:
The += assignment operator can also be used to add (concatenate) strings:
Example
txt1 += "nice day";
The result of txt1 will be:
Adding Strings and Numbers
Adding two numbers, will return the sum, but adding a number and a string will return a string:
Example
y = "5" + 5;
z = "Hello" + 5;
The result of x, y, and z will be:
55
Hello5
The rule is: If you add a number and a string, the result will be a string!
JavaScript Comparison and Logical Operators
Operator | Description |
---|---|
== | equal to |
=== | equal value and equal type |
!= | not equal |
!== | not equal value or not equal type |
> | greater than |
< | less than |
>= | greater than or equal to |
<= | less than or equal to |
? | ternary operator |
Comparison and logical operators are described in the JS Comparisons chapter.
JavaScript Type Operators
Operator | Description |
---|---|
typeof | Returns the type of a variable |
instanceof | Returns true if an object is an instance of an object type |
Type operators are described in the JS Type Conversion chapter.