获取数据属性 onchange 事件

Question

我正在尝试检索我添加到选项元素的自定义数据属性，但它不起作用。

<p>Select a new car from the list.</p>

<select id="mySelect" onchange="myFunction(this.data-price)">
  <option data-price="250" value="Audi">Audi</option>
  <option data-price="130" value="BMW">BMW</option>
  <option data-price="120" value="Mercedes">Mercedes</option>
  <option data-price="400" value="Volvo">Volvo</option>
</select>

<p>When you select a new car, a function is triggered which outputs the value of the selected car.</p>
<p id="demo"></p>

function myFunction(val) {
  document.getElementById("demo").innerHTML = "You selected: " + val;
  console.log(val);
}

问题是当我将函数调用切换到：

onchange="myFunction(this.value)">

它会正确返回值，但是当我选择数据价格时，它会将undefined 返回到控制台。

Answer 1

您的代码说“获取数据属性”并从中减去变量“价格”。第二个问题，当它位于选项上时，您正在选择该选项上的属性。你不能把它当作价值来使用。

您应该在所选选项上使用dataset

function myFunction(sel) {
  var opt = sel.options[sel.selectedIndex];
  var price = opt.dataset.price
  document.getElementById("demo").innerHTML = "You selected: " + price;
}

<p>Select a new car from the list.</p>

<select id="mySelect" onchange="myFunction(this)">
  <option data-price="250" value="Audi">Audi</option>
  <option data-price="130" value="BMW">BMW</option>
  <option data-price="120" value="Mercedes">Mercedes</option>
  <option data-price="400" value="Volvo">Volvo</option>
</select>

<p>When you select a new car, a function is triggered which outputs the value of the selected car.</p>
<p id="demo"></p>

Answer 2

只需访问所选选项的数据属性（jQuery 示例，因为您已标记它）：

$("#mySelect").change(function() {
  const $this = $(this); // Cache $(this)
  const dataVal = $this.find(':selected').data('price'); // Get data value
  const selectedVal = $this[0].value;
  alert(`${dataVal}, ${selectedVal}`);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<p>Select a new car from the list.</p>

<select id="mySelect">
  <option data-price="250" value="Audi">Audi</option>
  <option data-price="130" value="BMW">BMW</option>
  <option data-price="120" value="Mercedes">Mercedes</option>
  <option data-price="400" value="Volvo">Volvo</option>
</select>

<p>When you select a new car, a function is triggered which outputs the value of the selected car.</p>
<p id="demo"></p>