JS 무작위로 정렬된 배열 예제 분석

function randomOrder (targetArr) {
  var originalArr = targetArr;
  var newArr = [];
  var arrLength = targetArr.length;
  var j = -1;
  var tmpObj = {};
  for(var i = 0;i < arrLength;i++){
    while(true) {
      if(tmpObj[j = parseInt(arrLength * Math.random())] == undefined) {
        tmpObj[j] = 1;
        console.log(j);
        break;
      }
    }
    newArr[i] = originalArr[j];
  }
  return newArr;
}

function sortNumber(a,b) {
  return Math.random() - 0.5;
}
var arr = arr=[9,3,1,2,5,8,4,7,6,0];
arr.sort(sortNumber);