Operator | Description | Comment |
/* */ // |
encloses multi-line comment indicates rest of line is a comment |
|
= | assignment | |
; | terminates a line (optional) | x = 1 or x = 1; are both acceptable in
JavaScript Note: semi-colons can be used to separate more than one statement on a line but this style of coding is inadvisable. |
== | checks for equality, e.g. if (x==1) |
if you use single = when trying to check for
equality: if(j=5) {statement} then the expression evaluates to true and the expression is also executed (j is assigned 5). This is comparable to bug-prone C behaviour |
!= > >= < <= |
checks for inequality greater than, gr. than or equal less than, less than or equal |
|
! | NOT (negates a boolean expression) | |
+= -= *= | shorthand operator to add/subtract/multiple two numbers and assign to first | x += s (is like x = x + s, doing addition or string concat. depending on whether these are numbers or strings) |
++ -- | quick increment (decrement) | x++ is like x = x + 1 |
&& || |
Logical and, Logical or respectively. |
(a && b) if a is false, b is not
evaluated (or executed) (a || b) if a is true, b is not evaluated (or executed) |
a ? b : c | Conditional operator | if boolean expr. "a" is true, use expr. "b", otherwise use expr. "c" |