<template>: The Content Template element

The <template> HTML element serves as a mechanism for holding HTML fragments, which can either be used later via JavaScript or generated immediately into shadow DOM.

Attributes

This element includes the global attributes.

shadowrootmode

Creates a shadow root for the parent element. It is a declarative version of the Element.attachShadow() method and accepts the same enumerated values.

open

Exposes the internal shadow root DOM for JavaScript (recommended for most use cases).

closed

Hides the internal shadow root DOM from JavaScript.

Note: This is a feature of the HTML parser that cannot be used post-parsing by setting the shadowrootmode attribute through JavaScript. Only allowed values will create the shadow root; any other values, including empty ones, won't trigger this behavior.

Note: You may find the non-standard shadowroot attribute in older tutorials and examples that used to be supported in Chrome 90-110. This attribute has since been removed and replaced by the standard shadowrootmode attribute.

Usage notes

There are two main ways to use the <template> element:

  1. By default, the element's content is not rendered, only parsed into a document fragment. Using the content property in JavaScript, this fragment can be cloned via the cloneNode method and inserted into the DOM.
  2. If the element contains the shadowrootmode attribute, the HTML parser will immediately generate a shadow DOM. The element is replaced in the DOM by its content wrapped in a shadow root.

The corresponding HTMLTemplateElement interface includes a standard content property (without an equivalent content/markup attribute). This content property is read-only and holds a DocumentFragment that contains the DOM subtree represented by the template. Be careful when using the content property because the returned DocumentFragment can exhibit unexpected behavior. For more details, see the Avoiding DocumentFragment pitfalls section below.

Examples

Generating table rows

First we start with the HTML portion of the example.

html
<table id="producttable">
  <thead>
    <tr>
      <td>UPC_Code</td>
      <td>Product_Name</td>
    </tr>
  </thead>
  <tbody>
    <!-- existing data could optionally be included here -->
  </tbody>
</table>

<template id="productrow">
  <tr>
    <td class="record"></td>
    <td></td>
  </tr>
</template>

First, we have a table into which we will later insert content using JavaScript code. Then comes the template, which describes the structure of an HTML fragment representing a single table row.

Now that the table has been created and the template defined, we use JavaScript to insert rows into the table, with each row being constructed using the template as its basis.

js
// Test to see if the browser supports the HTML template element by checking
// for the presence of the template element's content attribute.
if ("content" in document.createElement("template")) {
  // Instantiate the table with the existing HTML tbody
  // and the row with the template
  const tbody = document.querySelector("tbody");
  const template = document.querySelector("#productrow");

  // Clone the new row and insert it into the table
  const clone = template.content.cloneNode(true);
  let td = clone.querySelectorAll("td");
  td[0].textContent = "1235646565";
  td[1].textContent = "Stuff";

  tbody.appendChild(clone);

  // Clone the new row and insert it into the table
  const clone2 = template.content.cloneNode(true);
  td = clone2.querySelectorAll("td");
  td[0].textContent = "0384928528";
  td[1].textContent = "Acme Kidney Beans 2";

  tbody.appendChild(clone2);
} else {
  // Find another way to add the rows to the table because
  // the HTML template element is not supported.
}

The result is the original HTML table, with two new rows appended to it via JavaScript:

Implementing a declarative shadow DOM

In this example, a hidden support warning is included at the beginning of the markup. This warning is later set to be displayed via JavaScript if the browser doesn't support the shadowrootmode attribute. Next, there are two <article> elements, each containing nested <style> elements with different behaviors. The first <style> element is global to the whole document. The second one is scoped to the shadow root generated in place of the <template> element because of the presence of the shadowrootmode attribute.

html
<p hidden>
  ⛔ Your browser doesn't support <code>shadowrootmode</code> attribute yet.
</p>
<article>
  <style>
    p {
      padding: 8px;
      background-color: wheat;
    }
  </style>
  <p>I'm in the DOM.</p>
</article>
<article>
  <template shadowrootmode="open">
    <style>
      p {
        padding: 8px;
        background-color: plum;
      }
    </style>
    <p>I'm in the shadow DOM.</p>
  </template>
</article>
js
const isShadowRootModeSupported =
  HTMLTemplateElement.prototype.hasOwnProperty("shadowRootMode");

document
  .querySelector("p[hidden]")
  .toggleAttribute("hidden", isShadowRootModeSupported);

Avoiding DocumentFragment pitfalls

When a DocumentFragment value is passed, Node.appendChild and similar methods move only the child nodes of that value into the target node. Therefore, it is usually preferable to attach event handlers to the children of a DocumentFragment, rather than to the DocumentFragment itself.

Consider the following HTML and JavaScript:

HTML

html
<div id="container"></div>

<template id="template">
  <div>Click me</div>
</template>

JavaScript

js
const container = document.getElementById("container");
const template = document.getElementById("template");

function clickHandler(event) {
  event.target.append(" — Clicked this div");
}

const firstClone = template.content.cloneNode(true);
firstClone.addEventListener("click", clickHandler);
container.appendChild(firstClone);

const secondClone = template.content.cloneNode(true);
secondClone.children[0].addEventListener("click", clickHandler);
container.appendChild(secondClone);

Result

Since firstClone is a DocumentFragment, only its children are added to container when appendChild is called; the event handlers of firstClone are not copied. In contrast, because an event handler is added to the first child node of secondClone, the event handler is copied when appendChild is called, and clicking on it works as one would expect.

Technical summary

Content categories Metadata content, flow content, phrasing content, script-supporting element
Permitted content No restrictions
Tag omission None, both the starting and ending tag are mandatory.
Permitted parents Any element that accepts metadata content, phrasing content, or script-supporting elements. Also allowed as a child of a <colgroup> element that does not have a span attribute.
Implicit ARIA role No corresponding role
Permitted ARIA roles No role permitted
DOM interface HTMLTemplateElement

Specifications

Specification
HTML Standard
# the-template-element

Browser compatibility

BCD tables only load in the browser

See also