Question

你好，我试图让用户输入几个标记，最后给出最高分和最低分，但由于某种原因，它打印两次，第二次打印无限和想法？

    var gradeAwarded;
var gradeAwarded;
var repeate = true;
var max;
var A;
var B;
var C;
var F;

var repeat, studentArr = [], markArr = [];
while (repeat !== 'n' && repeat !== 'N'){
    studentArr.push(prompt("Enter Student Name: "));
    markArr.push(parseInt (prompt("Enter Student mark: ")));
    repeat = prompt ("Do you want to enter another student: y/n");
}  

Array.prototype.max = function() {
  return Math.max.apply(Math, markArr);
};

Array.prototype.min = function() {
  return Math.min.apply(Math, markArr);
};
var min = markArr.min();
var max = markArr.max();


if (markArr <0 || markArr >100){
    alert("Grate out of bounds");
}else if (markArr >= 83){
    gradeAwarded = "A";
    A = +1;
}else if (markArr >= 70){
    gradeAwarded = "B";
    B = +1;
}else if (markArr >= 50){
    gradeAwarded = "C";
    C = +1; 
}else if (markArr >= 0){
    gradeAwarded = "F";
    F = +1;                                                     
}

    document.write("The Highest mark was : "+max);
    document.write("The Lowest mark was : "+min);

Answer 1

你使用while循环，所以第二次运行脚本时它永远不会运行，因为repeat =='n'。 markArry被重置，这就是第二次运行脚本时无限制的原因。

你应该使用do while循环。像这样：

do {
  studentArr.push(prompt("Enter Student Name: "));
  markArr.push(parseInt (prompt("Enter Student mark: ")));
  repeat = prompt ("Do you want to enter another student: y/n");
}while(repeat !=='n' || repeat !=='N');

应该有效

Answer 2

必须是||而不是＆amp;＆amp;

while (repeat !== 'n' || repeat !== 'N'){
    studentArr.push(prompt("Enter Student Name: "));
    markArr.push(parseInt (prompt("Enter Student mark: ")));
    repeat = prompt ("Do you want to enter another student: y/n");
}

并且你应该清除或将 null 设置为重复变量和

JavaScript打印多次

2 个答案: