HTMLSelectElement.selectedOptions - Web APIs 编辑

The read-only HTMLSelectElement property selectedOptions contains a list of the <option> elements contained within the <select> element that are currently selected. The list of selected options is an HTMLCollection object with one entry per currently selected option.

An option is considered selected if it has an HTMLOptionElement.selected attribute.

Syntax

var selectedCollection = HTMLSelectElement.selectedOptions;

Value

An HTMLCollection which lists every currently selected HTMLOptionElement which is either a child of the HTMLSelectElement or of an HTMLOptGroupElement within the <select> element.

In other words, any option contained within the <select> element may be part of the results, but option groups are not included in the list.

If no options are currently selected, the collection is empty and returns a length of 0.

Example

In this example, a <select> element with a number of options is used to let the user order various food items.

HTML

The HTML that creates the selection box and the <option> elements representing each of the food choices looks like this:

<label for="foods">What do you want to eat?</label><br>
<select id="foods" name="foods" size="7" multiple>
  <option value="1">Burrito</option>
  <option value="2">Cheeseburger</option>
  <option value="3">Double Bacon Burger Supreme</option>
  <option value="4">Pepperoni Pizza</option>
  <option value="5">Taco</option>
</select>
<br>
<button name="order" id="order">
  Order Now
</button>
<p id="output">
</p>

The <select> element is set to allow multiple items to be selected, and it is 7 rows tall. Note also the <button>, whose role it is to trigger fetching the HTMLCollection of selected elements using the selected property.

JavaScript

The JavaScript code that establishes the event handler for the button, as well as the event handler itself, looks like this:

let orderButton = document.getElementById("order");
let itemList = document.getElementById("foods");
let outputBox = document.getElementById("output");

orderButton.addEventListener("click", function() {
  let collection = itemList.selectedOptions;
  let output = "";

  for (let i=0; i<collection.length; i++) {
    if (output === "") {
      output = "Your order for the following items has been placed: ";
    }
    output += collection[i].label;

    if (i === (collection.length - 2) && (collection.length < 3)) {
      output +=  " and ";
    } else if (i < (collection.length - 2)) {
      output += ", ";
    } else if (i === (collection.length - 2)) {
      output += ", and ";
    }
  }

  if (output === "") {
    output = "You didn't order anything!";
  }

  outputBox.innerHTML = output;
}, false);

This script sets up a click event listener on the "Order Now" button. When clicked, the event handler fetches the list of selected options using selectedOptions, then iterates over the options in the list. A string is constructed to list the ordered items, with logic to build the list using proper English grammar rules (including a serial comma).

Result

The resulting content looks like this in action:

Specifications

SpecificationStatusComment
HTML Living Standard
The definition of 'HTMLSelectElement.selectedOptions' in that specification.
Living StandardNo change from HTML5
HTML5
The definition of 'HTMLSelectElement.selectedOptions' in that specification.
RecommendationInitial definition.

Browser compatibility

BCD tables only load in the browser

See also

如果你对这篇内容有疑问,欢迎到本站社区发帖提问 参与讨论,获取更多帮助,或者扫码二维码加入 Web 技术交流群。

扫码二维码加入Web技术交流群

发布评论

需要 登录 才能够评论, 你可以免费 注册 一个本站的账号。
列表为空,暂无数据

词条统计

浏览:42 次

字数:7809

最后编辑:7年前

编辑次数:0 次

    我们使用 Cookies 和其他技术来定制您的体验包括您的登录状态等。通过阅读我们的 隐私政策 了解更多相关信息。 单击 接受 或继续使用网站,即表示您同意使用 Cookies 和您的相关数据。
    原文