Negating and negating again in javascript is meaningless_javascript skills

Operator~ means bitwise negation. On the surface, ~~ (reverse and then negate) is meaningless. In fact, floating point numbers can be turned into integers in JS.

Copy code The code is as follows:

<script> <br>var myArray = new Array(); <br>myArray.push("a"); <br>myArray.push("b"); <br>myArray.push("c"); <br>myArray .push("d"); <br><br>//Now we need to randomly take out an element from the array<br>var random = myArray[~~(Math.random()*myArray.length)]; // Math.random() returns a pseudo-random number between 0 and 1, which may be 0 but is always less than 1, [0,1) <br><br>var i = 7.94; <br>i = ~~i ; <br>alert(i); <br><br>var j = 7.34; <br>j = ~~j; <br>alert(j); <br><br></script>

As above, if there is no ~~, then the decimal is randomly obtained, and the decimal part of the decimal is removed, leaving the integer. As above i=7, j=7. However, this mechanism does not exist in C. A floating point number (float) cannot be bitwise inverted in C, and forced type conversion can be used in C (but there is no such mechanism in JS. Floating point numbers are converted to integers. ) achieves the same purpose (discarding the decimal part and retaining the integer part).