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Operator Precedence

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.

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 … , …

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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence