代码解释

 function chooseQ(){
            var questionNum;
            var arr = new Array();
            for(var i = 0, j; i < 5; i++){
               questionNum = Math.floor(1 + Math.random() * 20);
               for(j = 0; j < arr.length; j++){
                  if(arr[j] == questionNum)
                  break;
               }
               if(j == arr.length){
                  arr[j] = questionNum;
                  if(confirmV==""){
                     str1.push(questionNum);
                  }
                  else{
                     str2.push(questionNum);
                  }
                  controlNum = i;
                  printQ(questionNum);
               }
               else{
                  i--;
               }
            }
         }