Precedence of operators in JavaScript

Operator Precedence
Operator precedence in JavaScript is a set of rules. This rule controls the order in which operators execute when evaluating expressions. Operations with higher precedence are performed Mr. Foo the operators of lower precedence. For example, multiplication is performed prior to addition.

The following table lists the JavaScript operators by priority from highest to lowest. Operators with the same precedence are evaluated in order from left to right.

Where parentheses can be used to change the order of evaluation determined by the operator precedence. This means that the expression in parentheses should be evaluated all before it is used for the remainder of the expression.

z = * (3 + +)

There are five operators in the expression: =, *, (), +, and another +. Based on the rules for operator precedence, they are evaluated in the following order: (), +, +, *, =.

Binding nature

The binding determines the order in which operators with the same precedence are executed. Consider the following expression:

a OP b OP c

Left-associative (computed from left to right) is equivalent to enclosing the left subexpression with parentheses (a OP b) OP c , similar to right-to-left calculations a OP (b OP c) . The assignment operator is right-associative, so you can write:

a = b = 5;

athe result and b the value will be 5. This is because the return result of the assignment operator is the value to the right of the assignment operator, which is b assigned a value of 5 and is then a assigned b=5 the return value, which is 5.

Summary table

The following table arranges all operators from highest to lowest in priority order.

priority (high-to-low)	type of Operation	Relevance of	operator
19	圆括号	N/A	( … )
18	成员访问	From left to right	… . …
	需计算的成员访问	From left to right	… [ … ]
	new(with parameter list)	N/A	new … ( … )
17	Function call	From left to right	… ( … )
	New (no parameter list)	From right to left	new …
16	Post increment (operator behind)	N/A	… ++
	Post decrement (operator behind)	N/A	… --
15	Logical Non-	From right to left	! …
	Bitwise non-	From right to left	~ …
	One-dollar addition	From right to left	+ …
	One-dollar subtraction	From right to left	- …
	Forward increment	From right to left	++ …
	Forward Decrement	From right to left	-- …
	typeof	From right to left	typeof …
	void	From right to left	void …
	Delete	From right to left	delete …
14	Multiplication	From left to right	… * …
	Division	From left to right	… / …
	Take the mold	From left to right	… % …
13	Addition	From left to right	… + …
	Subtraction	From left to right	… - …
12	Bitwise LEFT Shift	From left to right	… << …
	Bitwise RIGHT SHIFT	From left to right	… >> …
	Unsigned Right Shift	From left to right	… >>> …
11	Less than	From left to right	… < …
	Less than or equal	From left to right	… <= …
	Greater than	From left to right	… > …
	Greater than or equal	From left to right	… >= …
	Inch	From left to right	… in …
	instanceof	From left to right	… instanceof …
10	Equals	From left to right	… == …
	Non-equal sign	From left to right	… != …
	Full equals	From left to right	… === …
	Non-full equals	From left to right	… !== …
9	Bitwise-AND	From left to right	… & …
8	Bitwise XOR OR	From left to right	… ^ …
7	Bitwise OR	From left to right	… | …
6	Logic and	From left to right	… && …
5	Logical OR	From left to right	… || …
4	Conditional operators	From right to left	… ? … : …
3	Assign value	From right to left	… = …
			… += …
			… -= …
			… *= …
			… /= …
			… %= …
			… <<= …
			… >>= …
			… >>>= …
			… &= …
			… ^= …
			… |= …
2	Yield	From right to left	yield …
	yield*	From right to left	Yield* ...
1	Expand operator	N/A	......
0	Comma	From left to right	… , …

Precedence of operators in JavaScript