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Operator precedence determines the way in which operators are parsed with respect to each other. Operators with higher precedence become the operands of operators with lower precedence.
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Associativity
Associativity determines the way in which operators of the same precedence are parsed. For example, consider an expression:
a OP b OP c
Left-associativity (left-to-right) means that it is processed as (a OP b) OP c, while right-associativity (right-to-left) means it is interpreted as a OP (b OP c). Assignment operators are right-associative, so you can write:
a = b = 5;
with the expected result that a and b get the value 5. This is because the assignment operator returns the value that is assigned. First, b is set to 5. Then the a is also set to 5, the return value of b = 5, aka right operand of the assignment.
Table
The following table is ordered from highest (20) to lowest (1) precedence.
| Precedence | Operator type | Associativity | Individual operators |
|---|---|---|---|
| 20 | Grouping |
n/a | ( … ) |
| 19 | Member Access |
left-to-right | … . … |
Computed Member Access |
left-to-right | … [ … ] |
|
new (with argument list) |
n/a | new … ( … ) |
|
| Function Call | left-to-right | … ( … ) |
|
| 18 | new (without argument list) |
right-to-left | new … |
| 17 | Postfix Increment |
n/a | … ++ |
Postfix Decrement |
… -- |
||
| 16 | Logical NOT | right-to-left | ! … |
| Bitwise NOT | ~ … |
||
| Unary Plus | + … |
||
| Unary Negation | - … |
||
| Prefix Increment | ++ … |
||
| Prefix Decrement | -- … |
||
| typeof | typeof … |
||
| void | void … |
||
| delete | delete … |
||
| await | await … |
||
| 15 | Exponentiation | right-to-left | … ** … |
| 14 | Multiplication | left-to-right | … * … |
| Division | … / … |
||
| Remainder | … % … |
||
| 13 | Addition | left-to-right | … + … |
| Subtraction | … - … |
||
| 12 | Bitwise Left Shift | left-to-right | … << … |
| Bitwise Right Shift | … >> … |
||
| Bitwise Unsigned Right Shift | … >>> … |
||
| 11 | Less Than | left-to-right | … < … |
| Less Than Or Equal | … <= … |
||
| Greater Than | … > … |
||
| Greater Than Or Equal | … >= … |
||
| in | … in … |
||
| instanceof | … instanceof … |
||
| 10 | Equality | left-to-right | … == … |
| Inequality | … != … |
||
| Strict Equality | … === … |
||
| Strict Inequality | … !== … |
||
| 9 | Bitwise AND | left-to-right | … & … |
| 8 | Bitwise XOR | left-to-right | … ^ … |
| 7 | Bitwise OR | left-to-right | … | … |
| 6 | Logical AND | left-to-right | … && … |
| 5 | Logical OR | left-to-right | … || … |
| 4 | Conditional | right-to-left | … ? … : … |
| 3 | Assignment | right-to-left | … = … |
… += … |
|||
… -= … |
|||
… **= … |
|||
… *= … |
|||
… /= … |
|||
… %= … |
|||
… <<= … |
|||
… >>= … |
|||
… >>>= … |
|||
… &= … |
|||
… ^= … |
|||
… |= … |
|||
| 2 | yield | right-to-left | yield … |
| yield* | yield* … |
||
| 1 | Comma / Sequence | left-to-right | … , … |