Operators
An operator performs some operation on single or multiple operands and produces a result.
/* Most operators are binary or unary
<left operand> operator <right operand>
<left operand> operator
*/
Arithmetic
| Operator | Description |
|---|
| + |
Addition. Can be used with strings.
a = 23+b;
var nick="Nick"+10; // result string "Nick10"
var name=23 +"Name"+10; // result string "23Name10"
|
| - | Subtraction
var a = b-10;
|
| * | Multiplication
var a = b*10;
|
| ** | Exponentiation
var a = 2**3; // now a equal to 8
|
| / | Division
a = b/10;
|
| % | Remainder
a = 24%10; // result 4
|
| ++ | Increment. You can use postfix increment or prefix increment.
var ind=10;
ind++; // now ind equal to 11
var x = ind++; // now x equal to 11, ind equal to 12
var y = ++ind; // now y and ind equal to 13
|
| -- | Decrement. You can use postfix decrement or prefix increment.
var ind=10;
ind--; // now ind equal to 9
|
Relational
| Operator | Description |
|---|
| == |
Is equal to. Before comparing, it tries to convert the type of the operands, so 2=='2' is true. See more examples of equality in Javascript.
|
| === | Is identical, i.e. both operands refer to the same object or operands have same type and value for primitive types.
if(a===b){
...
}
See more examples of equality in Javascript
|
| != | Not equal to
if(a!=34){
...
}
|
| !== | Not Identical
if(a!==b){
...
}
|
| < | Less than
var a = 23 < 45; // now a equal to true
|
| <= | Less than or equal to
var a = 46 <= 45; // now a equal to false
|
| > | Greater than
var a = 23 > 45;
|
| >= | Greater than or equal to
var a = 46 >= 45;
|
Bitwise
| Operator | Description |
|---|
| & |
Bitwise and
var a = 23&46; // now a equal to 6
|
| | |
Bitwise or
var a = 23|46; // now a equal to 63
|
| ^ |
Bitwise xor
var a = 23^46; // now a equal to 57
|
| ~ |
Bitwise not
var a = ~23; // now a equal to -24
|
| << |
Bitwise left shift
var a = 23<<4;// now a equal to 368
|
| >> |
Bitwise right shift
var a = 23>>4;// now a equal to 1
|
| >>> |
Bitwise right shift with zero
var a = 0xff>>>4;// now a equal to 15
|
Logical
| Operator | Description |
|---|
| && |
Logical and
if(a&&b){
...
}
|
| || |
Logical or
if(a||b){
...
}
|
| ! |
Logical not
if(!a){
...
}
|
Assigment
| Operator | Description |
|---|
| = |
Assign |
| += |
Add and assign
a+=10; // same as a = a + 10;
|
| -= |
Subtract and assign |
| *= |
Multiply and assign |
| **= |
Exponentiate and assign
a**=3; // same as a = a *** 3;
|
| /= |
Divide and assign. |
| %= |
Take the remainder and assign |
Other operators
| Operator | Description |
|---|
| () |
Expression grouping or function call |
| (?:) |
Conditional operator; returns value based on the condition like if-else.
// syntax
// expr ? val1 : val2
// if expr equal to true then return first value, otherwise second
var a= x>y ? 23 : 45 ;
|
| , |
Allows multiple expressions to be evaluated as single statement.
var a=2, b=a+6;
|
| new |
Create instance of object |
| in |
Checks if object has the given property. |
| instanceof |
Checks if the object is an instance of given type. |
| typeof |
Checks the type of object. |
truthy and falsey values
As you know, in some cases JavaScript tries to convert the type.
In the case of boolean expressions, the following values are considered to be falsey:
- "" (empty string)
- 0
- null
- undefined
- NaN
Following values are considered to be truthy:
- {} (any object)
- [] (any array)
- "hello world" (non-empty string)
- 123 (non-zero number)
You can use double negation to convert a value to a boolean value.
console.log( typeof !!"hello world" === 'boolean'); // true