JavaScript Operators

JavaScript Operators

Example

Assign values to variables and add them together:

var x = 7;		// Assign the value 7 to x
var y = 8;		// Assign the value 8 to y
var z = x + y;		// Assign the value 15 to z (x + y)

Try it yourself

AssignmentOperator (=）Assign a value to the variable.

Assignment

var x = 15;

Try it yourself

AdditionOperator (+）Add numbers:

Addition

var x = 7;
var y = 8;
var z = x + y;

Try it yourself

MultiplicationOperator (*）Multiply numbers:

Multiplication

var x = 7;
var y = 8;
var z = x * y;

Try it yourself

JavaScript Arithmetic Operators

Arithmetic operators are used to perform arithmetic operations on numbers:

Operator Description
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulus (remainder)
++ Increment
-- Decrement

Note:JS ArithmeticThis chapter fully describes arithmetic operators.

JavaScript Assignment Operator

The assignment operator assigns a value to the JavaScript variable.

Operator Example Is equivalent to
= 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

Addition assignment operator (+=）Add a value to the variable.

Assignment

var x = 7;
x += 8;

Try it yourself

Note:JS AssignmentThis chapter fully describes the assignment operator.

JavaScript String Operators

+ The operator can also be used to concatenate (concatenate, cascading) strings.

Example

txt1 = "Bill";
txt2 = "Gates";
txt3 = txt1 + " " + txt2;

The result of txt3 will be:

Bill Gates

Try it yourself

+= The assignment operator can also be used to add (cascading) strings:

Example

txt1 = "Hello ";
txt1 += "Kitty!";

The result of txt1 will be:

Hello Kitty!

Try it yourself

Tip:When used for strings:+ The operator is called the cascading operator.

Addition of strings and numbers

Adding two numbers will return the sum, but adding a number and a string will return a string:

Example

x = 7 + 8;
y = "7" + 8;
z = "Hello" + 7;

The result of x, y, and z will be:

15
78
Hello7

Try it yourself

Tip:If you add a number and a string, the result will be a string!

JavaScript Comparison Operators

Operator Description
== Equal
=== Equal value and type
!= Not equal
!== Unequal value or type
> Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
? Trinary operator

Note:JS ComparisonThis chapter fully describes the comparison operators.

JavaScript Logical Operators

Operator Description
&& Logical AND
|| Logical OR
! Logical NOT

Note:JS ComparisonThis chapter fully describes the logical operators.

JavaScript Type Operators

Operator Description
typeof Returns the type of the variable.
instanceof Returns true if the object is an instance of the object type.

Note:JS Type ConversionThis chapter fully describes the type operators.

JavaScript Bitwise Operators

Bitwise operators handle 32-bit numbers.

Any numeric operand in this operation will be converted to a 32-bit number. The result will be converted back to a JavaScript number.

Operator Description Example Is equivalent to Result Decimal
& AND 5 & 1 0101 & 0001 0001 1
| OR 5 | 1 0101 | 0001 0101 5
~ NOT ~5 ~0101 1010 10
^ XOR 5 ^ 1 0101 ^ 0001 0100 4
<< Zero-filled left shift 5 << 1 0101 << 1 1010 10
>> Signed right shift 5 >> 1 0101 >> 1 0010 2
>>> Zero-filled right shift 5 >>> 1 0101 >>> 1 0010 2

The previous example uses a 4-bit unsigned example. However, JavaScript uses 32-bit signed numbers.

Therefore, in JavaScript, ~5 will not return 10, but -6.

~00000000000000000000000000000101 will return 11111111111111111111111111111010.

Note:We will JS BitwiseThis chapter explains bitwise operators in detail.

textbook

For more information on JavaScript OperatorsFor more information on the knowledge, please read the relevant content in the advanced JavaScript tutorial:

ECMAScript Unary Operators
Unary operators have only one parameter, which is the object or value to be operated on. This section explains the simplest operator in ECMAScript - unary operator.
ECMAScript Bitwise Operators
Bitwise operators operate at the low level of numbers. This section delves into the knowledge of integers and introduces various bitwise operators of ECMAScript.
ECMAScript Boolean Operators
Boolean operators are very important. This section delves into the three Boolean operators: NOT, AND, and OR.
ECMAScript Multiplicative Operators
This section explains the multiplicative operators of ECMAScript: multiplication, division, and modulus operators, as well as their special behaviors.
ECMAScript Additive Operators
This section explains the additive operators of ECMAScript: addition, subtraction operators, and their special behaviors.
ECMAScript Relational Operators
Relational operators perform comparison operations. This section explains the conventional comparison methods of relational operators, as well as how to compare strings with numbers.
ECMAScript Equality Operators
Equality operators are used to determine if variables are equal. ECMAScript provides two sets of equality operators: equal to and not equal to, as well as strictly equal to and strictly not equal to.
ECMAScript Conditional Operators
This section explains the conditional operator in ECMAScript.
ECMAScript Assignment Operators
This section explains the assignment operator in ECMAScript.
ECMAScript Comma Operator
This section explains the comma operator in ECMAScript.

See Also

Tutorial:JavaScript Operator Precedence

Reference Manual:JavaScript Operators