# Some details about bitwise anti-operators in Javascript

Source: Internet
Author: User

Executes bitwise non (evaluate not) operations on an expression.

Result = ~ Expression

Parameters

Result
Any variable.

Expression

Any expression.

Remarks

All unary operators (such ~ Operators) are calculated according to the following rules:

• If it is applied to an undefined or null expression, a runtime error is thrown.

• Convert an object to a string.

• If possible, convert the string to a number. Otherwise, a running error occurs.

• The Boolean value is regarded as a number (if it is false, it is 0; if it is true, it is 1 ).

The operator is applied to the result number.

~ Operator to view the value in the binary representation of the expression and perform a bit non-operation.

If any one of the bits in the expression is 1, the bit in the result is 0. If any one of the bits in the expression is 0, the bit in the result is changed to 1.

The following example illustrates the bitwise (~) Operator usage.

Var temp = ~ 5;

The value is-6, as shown in the following table.

Expression

Binary value (complement of 2)
Decimal Value

5
00000000 00000000 00000000 00000101
5

~ 5
11111111 11111111 11111111 11111010
-6

The following example illustrates the bitwise (~) The usage of the operator, which contains binary numbers that indicate negative decimal numbers. If you are not familiar with this operation, please first understand
Var temp = ~ 5;
/*
5 binary 101, full 32 bits
00000000000000000000000000000101
Bitwise Inversion
11111111111111111111111111111010
Because the first one starting with 32 bits is 1, this is a negative number. to convert the binary into a negative number, we need to reverse code it first.
00000000000000000000000000000101
Then, + 1
00000000000000000000000000000110
Convert to 6 in decimal format, and add the symbol to negative number-6.
*/
// Pop up [-6]

Bit operations

There are 7 javascript bit operations

& | ^ ~ <>>>>

Bitwise AND (&)

If the two numbers have the same bit of 1, 1 is returned. Otherwise, 0 is returned,

For example, the binary value of 1 & 2 = 0010 is 0000, And the binary value of is.

0001

0010

-------

0000

The result is 0.

By bit or (|)

When only one of the two numbers is 1, it is 1 2 | 1 = 3.

0010

0001

-------

0011

3.

Non-(^) by bit)

The corresponding bitwise of the two operands is 1, otherwise it is 9 ^ 6 = 15

1001

0110

-------

1111

15.

Bit non (~)

Bitwise non-operator "~" Bitwise inversion of operands, which is a single-object Operator

Bitwise NOT, as the name implies, returns the inverse of the operand. ~ 7 =-8

0111

------ ==========> At the beginning, there should be a symbol, so it is-8.

1000

Shift left (<)

The Left shift operator <implements the function of Population 0 by moving the base position to the left. It is a binary operator.

15 <2 = 60

0000 1111

0011 1100

Move left (>)

The Left shift operator ">" is used to add 0 to the Base position of the entire Left Movement. It is a binary operator.

15> 2 = 3

0000 1111

0000 0011

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