From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/html/element%2Ftemplate.html | 179 +++++++++++++++++++++++++++++++++++ 1 file changed, 179 insertions(+) create mode 100644 devdocs/html/element%2Ftemplate.html (limited to 'devdocs/html/element%2Ftemplate.html') diff --git a/devdocs/html/element%2Ftemplate.html b/devdocs/html/element%2Ftemplate.html new file mode 100644 index 00000000..d851df81 --- /dev/null +++ b/devdocs/html/element%2Ftemplate.html @@ -0,0 +1,179 @@ +

<template>: The Content Template element

+

The <template> HTML element is a mechanism for holding HTML that is not to be rendered immediately when a page is loaded but may be instantiated subsequently during runtime using JavaScript.

Think of a template as a content fragment that is being stored for subsequent use in the document. While the parser does process the contents of the <template> element while loading the page, it does so only to ensure that those contents are valid; the element's contents are not rendered, however.

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Attributes

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The only standard attributes that the <template> element supports are the global attributes.

In Chromium-based browsers, the <template> element also supports a non-standard shadowrootmode attribute, as part of an experimental "Declarative Shadow DOM" proposal. In supporting browsers, a <template> element with the shadowrootmode attribute is detected by the HTML parser and immediately applied as the shadow root of its parent element. shadowrootmode can take a value of open or closed; these are equivalent to the open and closed values of the Element.attachShadow() mode option.

Also, 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.

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Examples

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First we start with the HTML portion of the example.

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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.

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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:

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+ + +
+
+

Avoiding DocumentFragment pitfalls

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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:

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+

HTML

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+

html

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

JavaScript

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+

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

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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.

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Technical summary

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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
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Specifications

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Specification
HTML Standard
# the-template-element
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Browser compatibility

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+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariWebView AndroidChrome AndroidFirefox for AndroidOpera AndroidSafari on IOSSamsung Internet
template261322No158Yes26221481.5
shadowrootmode11190–11111190–111NoNo9776–9716.411190–11111190–111No6416.422.015.0–22.0
+

See also

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+

+ © 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
+ https://developer.mozilla.org/en-US/docs/Web/HTML/Element/template +

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