<summary>: The Disclosure Summary element

The <summary> HTML element specifies a summary, caption, or legend for a <details> element's disclosure box. Clicking the <summary> element toggles the state of the parent <details> element open and closed.

This element only includes the global attributes.

The <summary> element's contents can be any heading content, plain text, or HTML that can be used within a paragraph.

A <summary> element may only be used as the first child of a <details> element. When the user clicks on the summary, the parent <details> element is toggled open or closed, and then a toggle event is sent to the <details> element, which can be used to let you know when this state change occurs.

If a <details> element's first child is not a <summary> element, the user agent will use a default string (typically "Details") as the label for the disclosure box.

Per the HTML specification, the default style for <summary> elements includes display: list-item. This makes it possible to change or remove the icon displayed as the disclosure widget next to the label from the default, which is typically a triangle.

You can also change the style to display: block to remove the disclosure triangle.

See the Browser compatibility section for details, as not all browsers support full functionality of this element yet.

Below are some examples showing <summary> in use. You can find more examples in the documentation for the <details> element.

A simple example showing the use of <summary> in a <details> element:

<details open>
  <summary>Overview</summary>
  <ol>
    <li>Cash on hand: $500.00</li>
    <li>Current invoice: $75.30</li>
    <li>Due date: 5/6/19</li>
  </ol>
</details>

You can use heading elements in <summary>, like this:

<details open>
  <summary><h4>Overview</h4></summary>
  <ol>
    <li>Cash on hand: $500.00</li>
    <li>Current invoice: $75.30</li>
    <li>Due date: 5/6/19</li>
  </ol>
</details>

This currently has some spacing issues that could be addressed using CSS.

This example adds some semantics to the <summary> element to indicate the label as important:

<details open>
  <summary><strong>Overview</strong></summary>
  <ol>
    <li>Cash on hand: $500.00</li>
    <li>Current invoice: $75.30</li>
    <li>Due date: 5/6/19</li>
  </ol>
</details>

• <details>