Operator precedence is a set of rules in JScript that controls the order in which the compiler performs operations when evaluating an expression. Operations with a higher precedence are performed before those with a lower one. For example, multiplication is performed before addition.
Precedence Table
The following table lists the JScript operators, ordered from highest to lowest precedence.
Precedence  Evaluation Order  Operator  Description 

15 
left to right 
., [], () 
Field access, array indexing, function calls, and expression grouping 
14 
right to left 
++, , , ~, !, delete, new, typeof, void 
Unary operators, return data type, object creation, undefined values 
13 
left to right 
*, /, % 
Multiplication, division, modulo division 
12 
left to right 
+,  
Addition and string concatenation, subtraction 
11 
left to right 
<<, >>, >>> 
Bit shifting 
10 
left to right 
<, <=, >, >=, instanceof 
Less than, less than or equal, greater than, greater than or equal, instanceof 
9 
left to right 
==, !=, ===, !== 
Equality, inequality, strict equality, and strict inequality 
8 
left to right 
& 
Bitwise AND 
7 
left to right 
^ 
Bitwise XOR 
6 
left to right 
 
Bitwise OR 
5 
left to right 
&& 
Logical AND 
4 
left to right 
 
Logical OR 
3 
right to left 
?: 
Conditional 
2 
right to left 
=, OP= 
Assignment, compound assignment 
1 
left to right 
, (comma) 
Multiple evaluation 
Parentheses in an expression alter the order of evaluation determined by operator precedence. This means that an expression within parentheses is fully evaluated before its value is used in the remainder of the expression.
For example:
В  Copy Code 

z = 78 * (96  3 + 45) 
There are five operators in the preceding expression: =, *, (), , and +. According to the rules of operator precedence, they are evaluated in the following order: (), , +, *, =.

Evaluation of the expression within the parentheses occurs first. Within the parentheses, there is an addition operator and a subtraction operator. The operators both have the same precedence, and they are evaluated from left to right. The number 3 is subtracted from 96 first, resulting in 93. Then the number 45 is added to 93, resulting in a value of 139.

Multiplication occurs next. The number 78 is multiplied by the number 139, resulting in a value of 10764.

Assignment occurs last. The number 10764 is assigned to
z
.