Example
Assign values to variables and add them together:
var x = 5; // assign the value 5 to
x
var y = 2; // assign the value
2 to y
var z = x + y; // assign the value 7 to z (x + y)
Try it Yourself
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
txt1 = "John";
txt2 = "Doe";
txt3 = txt1 + " " + txt2;
The result of txt3 will be:
John Doe
Try it Yourself
The += assignment operator can also be used to add (concatenate) strings:
Example
txt1 = "What a very ";
txt1 += "nice day";
The result of txt1 will be:
What a very nice day
Try it Yourself
Adding Strings and Numbers
Adding two numbers, will return the sum, but adding a number and a string will return a string:
Example
x = 5 + 5;
y = "5" + 5;
z = "Hello" + 5;
The result of x, y, and z will be:
10
55
Hello5
Try it Yourself
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.