Operators

Arithmetic

Binary operators
+     Addition
-     Subtraction
*     Multiplication
/     Division (returns a floating-point value)
%     Modulus (returns the integer remainder)
Unary operators
-     Unary negation (reverses the sign)
++    Increment (can be prefix or postfix) 
--    Decrement (can be prefix or postfix)

Assignment

=     Assign

+=    Add and assign
-=    Subtract and assign
*=    Multiply and assign
/=    Divide and assign
%=    Modulus and assign

&=    Bitwise AND and assign
|=    Bitwise OR and assign
^=    Bitwise XOR and assign

<<=   Left shift (zero fill) and assign
>>=   Right shift (sign-propogating) and assign
>>>=  Right shift (zero fill) and assign

Comparison

==    Equal
!=    Not equal
>     Greater than
>=    Greather than or equal to
<     Less than
<=    Less than or equal to

===   Identical (equal and of the same type)
!==   Not identical

Conditional

? :   Ternary comparison operator

      condition ? val1 : val2  (Evaluates val1 if condition is true; otherwise, evaluates val2)

Boolean

  • Short-circuit logical operations
  • Evaluates the minimal number of expressions necessary
  • Partial evaluation (rather than full evaluation) 
&&    and
||    or
!     not (logical negation)

Bitwise

Binary operators
&     And
|     Or
^     Xor

<<    Shift left (zero fill) 
>>    Shift right (sign-propogating); copies of the leftmost bit (sign bit) are shifted in from the left. 
>>>   Shift right (zero fill)

      For positive numbers, >> and >>> yield the same result.
Unary operators
~     Not (inverts the bits)

String

=     Assignment
+     Concatenation
+=    Concatenate and assign
Examples
str = "ab" + "cd";   // "abcd"
str += "e";          // "abcde"

Misc

typeof

typeof operand
typeof (operand)
  • Results in one of the following values: "function", "number", "boolean", "string", "object", "undefined"