Javascript计算器（有困难）

Question

我正在上入门编码课程，我们刚刚开始学习 javascript。我们的第一个任务是创建一个简单的 JavaScript 计算器，它能够计算数字列表的总和、平均值、最大值和最小值。我的老师说这可以通过多种方式完成，但他推荐了一种叫做“for”循环的东西。我在 css 和 html 方面表现不错，但我一直在努力使用 javascript。任何帮助将不胜感激。

html:

<h4>1,3,9,6,5,7,12,32</h4>
        <input type="text" id="valueList"><button type="button" id="calculate">Calculate Stats</button>
        <br><br>
        <H2>Results</H2>
<ul id="results"><!--javascript will write items here--></ul>

jss:

var valueSum = 0;
var valueAverage = 0; 
var valueMax = 0;
var valueMin = 0; 

$( "#calculate" ).click(processValues);

function processValues() {//listens for click event
  $("#results" ).html( "" );//clears any list items from last calculation
  var valueString = $( "#valueList" ).val();
  var value = $.map(valueString.split(","), Number ); //this is an array
  valueCount = value.length; //get the lenght of the array (number of values)
  //
  //Use a loop (or loops) here to help calculate the sum, average, max, and min of the values
  //



  $("#results" ).append( "<li>The values entered: " + valueString + ".</li>" );//appends values
  $("#results" ).append( "<li>There are " + valueCount + " values.</li>" );//appends value count

  //need to append Sum, average, max, and min to bullet list here

  //clears text field for next set of values to be entered
  $("#valueList").v

Answer 1

好的，想想如果给你一个数字列表并想计算其中的每一个，你会在逻辑上做什么。

例如，您有一张纸，上面有数字列表，并且您想弄清楚哪个是最大数字，您要做的就是查看第一个数字，将其记在脑海中，然后继续扫描在列表中向下，直到找到一个大于该数字的数字。然后，您将继续扫描列表，直到找到一个大于该数字的数字，等等，直到您到达列表的末尾。这可以通过这样的 for 循环来实现

var maxSeen = value[0];

for (var i = 1; i < valueCount; i++) {
    var thisNumber = value[i];

    if (thisNumber > maxSeen) {
        maxSeen = thisNumber;
    }
}

console.log("max", maxSeen);

想想你将如何用笔和纸计算其他每个，然后谷歌“for循环”，看看你是否可以自己实现其余的。没有比实践更好的学习方式了。

Answer 2

这就是答案。

https://jsfiddle.net/5a3bndy9/

$( "#calculate" ).click(processValues);

function processValues() {

    var valueSum = 0;
    var valueAverage = 0; 
    var valueMax = 0;
    var valueMin = Infinity; 

  //listens for click event
  $("#results" ).html( "" );//clears any list items from last calculation
  var valueString = $( "#valueList" ).val();
  var value = $.map(valueString.split(","), Number ); //this is an array
  valueCount = value.length; //get the lenght of the array (number of values)

    //
  //Use a loop (or loops) here to help calculate the sum, average, max, and min of the values
  //

// loop to find sum
for (var i=0; i <= valueCount; i++)
{
    if (value[i] != undefined) // this check exists because your array includes undefined and it shouldn't
    { 
        valueSum += +value[i];
    }
}

// praxis to find average
valueAverage = valueSum / valueCount;

// loop to find max
for (var i=0; i <=valueCount; i++)
{
        if (value[i] != undefined) // this check exists because your array includes undefined and it shouldn't
        {
            if (value[i] > valueMax)
            {
                valueMax = value[i];
            }       
        }
}

//loop to find min
for (var i=0; i <=valueCount; i++)
{
        if (value[i] != undefined) // this check exists because your array includes undefined and it shouldn't
        {
            if (value[i] <= valueMin)
            {
                valueMin = value[i];
            }       
        }
}

  $("#results" ).append( "<li>The values sum is : " + valueSum + ".</li>" );//appends values
    $("#results" ).append( "<li>The values average is : " + valueAverage + ".</li>" );//appends values
    $("#results" ).append( "<li>The values max is : " + valueMax + ".</li>" );//appends values  
    $("#results" ).append( "<li>The values min is : " + valueMin + ".</li>" );//appends values  
  $("#results" ).append( "<li>There are " + valueCount + " values.</li>" );//appends value count

  //need to append Sum, average, max, and min to bullet list here

  }