Bitwise anti-operator in Javascript (~) _ Basic knowledge

Bitwise anti-operator (~) in Javascript (~), Executes bitwise non (evaluate not) operations on an expression. For example ~ 1-2 ;~ 2-3 ;~ 99-100 The Code is as follows:

Result = ~ [Number]

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

The Code is as follows:

1. If it is applied to an undefined or null expression, a runtime error is thrown.
2. convert an object to a string.
3. If possible, convert the string to a number. Otherwise, a running error occurs.
4. 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 (~) The usage of the operator, which contains binary numbers that represent negative decimal numbers. If you are not familiar with this operation, please first read "convert a decimal number to binary, octal, and hexadecimal".

The Code is as follows:

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.
*/
Alert (temp );
// Pop up [-6]