如何获得一个JavaScript析因程序循环来显示所使用的工作? [英] How to get a JavaScript factorial programs' loop to show the working used?

问题描述

您好，尽管我不太了解它，但我仍然面临用JavaScript编写程序的挑战，该程序会要求用户输入数字，然后计算该数字的阶乘.我使用已经问过的问题并设法使计算正常进行，但无法获得所需的输出.我必须在以下输出中获取它，而不使用任何奇特的库或额外的变量/数组(我想不出怎么做):

Hello there I have been challenged to write a program in JavaScript despite not really knowing much about it that asks the user for a number and then calculates the factorial of that number. I used already asked questions and managed to get the calculation to work but couldn't get the required output. I have to get it in the following output without using any fancy libraries or extra variables/arrays (which I can't think of how to do) :

(假设用户输入为5):

(assuming user input is 5):

The factorial of 5 is 5*4*3*2*1=120 
OR
5! is  5*4*3*2*1=120 

这是到目前为止我得到的代码:

Here is the code I've got so far:

//prompts the user for a positive number
var number = parseInt(prompt("Please enter a positive number"));
console.log(number);
//checks the number to see if it is a string
if (isNaN(number)) {
  alert("Invalid. Please Enter valid NUMBER")
}

//checks the number to see if it is negaive
else if (number < 0) {
  alert("Please Enter valid positive number");
}

//if a positive integer is entered a loop is started to calculate the factorial of the number the user entered
else {
  let factorial = 1;
  for (count = 1; count <= number; count++) {
    factorial *= count;
  }

  //Sends the inital number back to the user and tells them the factorial of that number
  alert("The factorial of " + number + " is " + factorial + ".");
}

我知道周围有很多类似的问题，并使用它们来帮助我进一步理解，但这是将输出转换为我正在努力使用的必需格式.有人告诉我有可能发生循环，但不知道从哪里开始实施，只能使用该解决方案.

I know there are many similar questions to this as I looked around and used them to help me get this far but it is getting the output into the required format that I'm struggling with. I am told it is possible with a loop but don't know where to begin implementing that and I'm only allowed to use that solution.

不幸的是，这是挑战中较大程序的一部分，我只能使用以下变量:

Unfortunately this is part of a larger program in the challenge and I can only use the following variables:

数字(变量初始化为0以容纳用户输入)阶乘(变量初始化为1以保存计算的阶乘的值)计数(可变以保持执行循环以执行阶乘计算的次数)

Number (variable initialised as 0 to hold user input) Factorial (variable initialised to 1 to hold value of calculated factorial) Count (variable to hold number of times loop is executed for performing factorial calculation)

推荐答案

可能您只需要在该循环中构建一个字符串即可(在计算实际值的基础上):

Probably you just need to build a string in that loop (on top of calculating the actual value):

let input=parseInt(prompt("Number?"));
let output="";
let result=1;
for(let i=input;i>1;i--){
  result*=i;
  output+=i+"*";
}
console.log(input+"! is "+output+"1="+result);

"no-array子句"在您的任务中大概意味着您不应该构建一个数组并在其上使用 join()，例如

The "no-array clause" in your task presumably means that you are not supposed to build an array and use join() on it, like

let arr=[1,2,3,4,5];
console.log(arr.join("*"));

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