via ToInt32. Its function is to flip the binary form of the operand bitwise. So two ~~ connected together are equivalent to the following operations:
Perform ToInt32 on the operand
Flip by bit
Bitwise flipping again actually still uses the absolute value rounding of ToInt32
In addition, there is a trick about the ~ operator that is quite practical: the value of ~(-1) is 0, and -1 is the only value that returns a false value after the ~ operation (including other ones Special values such as NaN, {}, [], etc. will not return false values) If the indexOf function of strings and arrays fails to search, it will return -1. At this time, you can use if(~str.indexOf('str ')) // To indicate that is found is more elegant than judging >= 0 or != -1 , and it is similar to using !! to judge non-false values
Rounding converts floating point numbers into 32-bit binary integers, so bit operations that can restore the state can be rounded, such as 23.5 >> 0 //23, 23.5 >> 0 //23 .
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Rounding converts floating point numbers into 32-bit binary integers, so bit operations that can restore the state can be rounded, such as
23.5 >> 0 //23,23.5 >> 0 //23.