javascript - 检查输入值是否减少/增加

Question

我有一个类型为 number 的 Input 并想检查它的值是否已减少/增加：

document.getElementById("myInput").addEventListener("change", function() {
    console.log(document.getElementById("myInput").value)

    // Check if Value has Increased/Decreased here
});

<input id="myInput" type = "number" value = "0">

帮助将不胜感激。谢谢！

标签： javascript

Answer 1

存储值并进行比较

var elem = document.getElementById("myInput");
elem.dataset.lastValue = elem.value;
elem.addEventListener("change", function() {

  const direction = +elem.value > +elem.dataset.lastValue ? 'increased' : 'decreased';
  console.log(direction);
  elem.dataset.lastValue = elem.value;
});

<input id="myInput" type="number" value="0">