Javascript 将文本区域输入转换为数组以计算平均总数

Question

我正在尝试让脚本根据输入到文本区域的数字计算平均值。数字用逗号分隔

我要么得到一个 NaN 值，要么就是不能正常工作。

此代码最接近实际工作。但是，它仅将逗号添加为新元素，并且所有数字仅组合在第一个元素中，将数字除以逗号的数量。

document.querySelector("#input").addEventListener("input", function test() {
  const strng = document.getElementById("input").value;
  var arr = strng.split(',');

  const avg = arr.reduce((a, b) => a + b, 0) / arr.length;
  document.getElementById("lbl").innerHTML = avg;
});


function cycle() {
  var area = document.getElementById("txt").value;
  var lines = area.split(',');

  const average = arr => arr.reduce((a, b) => a + b, 0) / arr.length;

  document.getElementById("lbl").innerHTML = average([lines]).toFixed(2);

}
setInterval(cycle, 100)

<textarea id="input"></textarea>
<label id="lbl">Result Here</label>
<textarea id="txt"></textarea>

cycle() 函数在文本区域中输入第一个逗号后立即给了我一个 NaN 值。

有人可以帮我吗？

Answer 1

当您从用户输入中拆分字符串时，您会得到一个字符串数组。因此，您必须在计算之前将这些字符串解析为数字并过滤掉任何非数字值。

function test() {
  const inputValue = document.getElementById("input").value;
  var values = inputValue.split(',').map(v => parseFloat(v)).filter(v => !Number.isNaN(v));

  const avg = values.reduce((a, b) => a + b, 0) / values.length;

  document.getElementById("lbl").innerHTML = (!Number.isNaN(avg)) ? avg : '';
}

setInterval(test, 100);

<textarea id="input"></textarea><br>
<label id="lbl">Result Here</label>
<textarea id="txt"></textarea>

Answer 2

// access the DOM elements
const inpTxt = document.getElementById("input");
const outTxt = document.getElementById("lbl");

// add event listener to text-area "input" event
inpTxt.addEventListener("input", () => {
  // collect the list of comma separated numbers into an array "numList"
  const numList = inpTxt
    .value                    // access the DOM element "inpTxt"'s value attribute
    .split(',')               // ".split()" using "comma" as the seperator
    .map(Number)              // convert each element into a number
    .filter(                  // sanity check to remove any non-number data
      x => !isNaN(x)
    );
  console.log(numList);       // to see in real-time the "numList" array on console
  if (numList.length) {       // if there are any valid numbers in the array
    outTxt.innerText = (      // change the "label"'s innerText
      numList.reduce(         // sum the numbers in the "numList" array
        (total, num) => total + num,
        0                     // initialize the "sum" to zero
      ) /                     // divide into "numList.length" to compute average
      numList.length
    );
  }
});

<div>
  Type comma-separated numbers in below input box
  and average will be calculated
</div>
<div><textarea id="input"></textarea></div>
<div><label id="lbl">Result Here</label></div>

Javascript 将文本区域输入转换为数组以计算平均总数

Javascript Convert Textarea input to Array to calculate average total

javascript

arrays

average