JavaScript Operators
The Addition Operator + adds numbers:
The Assignment Operator = assigns a value to a variable.
JavaScript Assignment
The Assignment Operator (=) assigns a value to a variable:
Assignment Examples
let x = 10;
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// Assign the value 5 to x
let x = 5;
// Assign the value 2 to y
let y = 2;
// Assign the value x + y to z:
let z = x + y;
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JavaScript Addition
The Addition Operator (+) adds numbers:
Adding
let x = 5;
let y = 2;
let z = x + y;
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JavaScript Multiplication
The Multiplication Operator (*) multiplies numbers:
Multiplying
let x = 5;
let y = 2;
let z = x * y;
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Types of JavaScript Operators
There are different types of JavaScript operators:
Arithmetic Operators
Assignment Operators
Comparison Operators
String Operators
Logical Operators
Bitwise Operators
Ternary Operators
Type Operators
JavaScript Arithmetic Operators
Arithmetic Operators are used to perform arithmetic on numbers:
Arithmetic Operators Example
let a = 3;
let x = (100 + 50) * a;
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Operator
Description
+
Addition
-
Subtraction
*
Multiplication
**
Exponentiation (ES2016)
/
Division
%
Modulus (Division Remainder)
++
Increment
--
Decrement
Note
Arithmetic operators are fully described in the
JS Arithmetic chapter.
JavaScript Assignment Operators
Assignment operators assign values to JavaScript variables.
The Addition Assignment Operator (+=) adds a value to a variable.
Assignment
let x = 10;x += 5;
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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
**=
x **= y
x = x ** y
Note
Assignment operators are fully described in the
JS Assignment chapter.
JavaScript Comparison 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
Note
Comparison operators are fully described in the
JS Comparisons chapter.
JavaScript String Comparison
All the comparison operators above can also be used on strings:
Example
let text1 = "A";
let text2 = "B";
let result = text1 < text2;
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Note that strings are compared alphabetically:
Example
let text1 = "20";
let text2 = "5";
let result = text1 < text2;
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JavaScript String Addition
The + can also be used to add (concatenate) strings:
Example
let text1 = "John";
let text2 = "Doe";
let text3 = text1 + " " + text2;
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The += assignment operator can also be used to add (concatenate) strings:
Example
let text1 = "What a very ";
text1 += "nice day";
The result of text1 will be:
What a very nice day
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Note
When used on strings, the + operator is called the concatenation operator.
Adding Strings and Numbers
Adding two numbers, will return the sum, but adding a number and a string will return a string:
Example
let x = 5 + 5;
let y = "5" + 5;
let z = "Hello" + 5;
The result of x, y, and z will be:
10
55
Hello5
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Note
If you add a number and a string, the result will be a string!
JavaScript Logical Operators
Operator
Description
&&
logical and
||
logical or
!
logical not
Note
Logical operators are fully 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
Note
Type operators are fully described in the JS Type Conversion chapter.
JavaScript Bitwise Operators
Bit operators work on 32 bits numbers.
Any numeric operand in the operation is converted into a 32 bit number.
The result is converted back to a JavaScript number.
Operator
Description
Example
Same as
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
<<
left shift
5 << 1
0101 << 1
1010
10
>>
right shift
5 >> 1
0101 >> 1
0010
2
>>>
unsigned right shift
5 >>> 1
0101 >>> 1
0010
2
The examples above uses 4 bits unsigned examples. But JavaScript uses 32-bit signed numbers.
Because of this, in JavaScript, ~ 5 will not return 10. It will return -6.
~00000000000000000000000000000101 will return 11111111111111111111111111111010
Bitwise operators are fully described in the JS
Bitwise chapter.
Test Yourself With Exercises
Exercise:
Multiply 10 with 5, and alert the result.
alert(10 5);
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Start the Exercise
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Reference: https://www.w3schools.com/js/js_operators.asp