为什么在我的数组中输入数字时会收到未定义的警报？

Question

当我将数字输入数组时，我收到两个警报：一个 "number" 警报，然后是一个 "undefined" 警报。我不知道如何解决这个问题。

这是我的 JavaScript 代码：

var myStuff = [];

function myfunctionA() {

  var enteredvalue = document.getElementById("numbers").value;

  alert(typeof Number(document.getElementById('numbers').value));
  if (enteredvalue == "") {
    alert("Input is not a number");

  } else if (isNaN(enteredvalue)) {
    alert('You need to enter a valid number!');
  }
  var elementExists = false;

  var x = document.getElementById('numbers').value;

  for (var i = 0; i < myStuff.length; i++) {
    if (myStuff[i] == Number(x)) {
      elementExists = true;
    }
  }

  if (elementExists != true) {
    myStuff.push(Number(enteredvalue));

    alert('Thank You for entering a valid number'. myStuff);
  } else {
    alert('Element is here');

  }
}

function myfunctionB() {
  window.alert(myStuff.length);
}

function myfunctionC() {
  var sum = 0;
  for (var i = 0; i < myStuff.length; i++) {
    sum += myStuff[i];
  }
  alert(sum);
}

function myfunctionD() {
  if (myStuff.length == 0) {
    alert("already empty");
  } else {
    myStuff = [];
  }
  alert("Array Empty");

}

function myfunctionE() {
  alert(myStuff.join('\n')); {
    if (myStuff == [])

    {
      alert("Enter something into Array")
    }
  }
}


function bubbleSort() {

  var sorted = true;
  var temp;
  while (sorted) {
    sorted = false;
    for (var i = 0; i < myStuff.length - 1; i++) {
      if (myStuff[i] < myStuff[i + 1]) {
        temp = myStuff[i];
        myStuff[i] = myStuff[i + 1];
        myStuff[i + 1] = temp;
        sorted = true;
      }
    }
  }
}

Answer 1

以下行评估为未定义：

alert('Thank You for entering a valid number'. myStuff);

你的意思是？：

alert('Thank You for entering a valid number' + myStuff);

为什么在我的数组中输入数字时会收到未定义的警报？

Why am I getting an undefined alert when entering a number into my array?

html

javascript

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