javascript - do the parantheses matter? -

Looking at this test

Why is it fast

  Var x; Var i = 1E4; Var j = 1e4; For (; i--> -1;) {x = - ~ x; } For (; j--> -1;) {x = ~ - x; }   
 From this?  
  var x; Var i = 1E4; Var j = 1E4; For (; j -> gt; -1;) {x = -1 * ~ x; } For (- j -> gt; -1;) {x = ~ (-1 * x); }   
 Is the second version better customizable, or what is the reason?   
 
 
 In the second code sample, you use j as an itater in both loops.