


What is the HTML Imports specification (and why was it deprecated)?
Jul 09, 2025 am 01:24 AMHTML Imports is a deprecated modular loading mechanism that allows the introduction of external HTML files through and use its contents in the current page. 1. It was used to encapsulate component structures, styles, and behaviors for reuse; 2. It was eliminated due to synchronous loading impacts performance, lack of module system support, inconsistent with the development direction of modern Web Components, and mainstream frameworks turning to JS modularity; 3. Alternatives include using ES Modules to define components in combination with Shadow DOM and Custom Elements, or using build tools to manage templates and component structures.
HTML Imports is a modular loading mechanism used in web development, allowing developers to import an HTML file into another HTML file. Simply put, it allows you to "take" the content of an external HTML document like you would refer to CSS.

But the technology has now been abandoned and replaced by more modern and flexible modular solutions, such as the combination of ES Modules and Web Components.
What is HTML Imports?
The core of HTML Imports is to introduce another HTML file through the <link>
tag. The basic writing method is as follows:

<link rel="import" href="component.html">
After it is introduced, the browser will download and parse the HTML file, which you can access through JavaScript and insert into the current page.
This practice was very popular in early Web Component development, especially in frameworks like Polymer. Its advantage is that component structures, styles, and behaviors can be encapsulated in one file and then reused across multiple pages.

Why was it abandoned?
While HTML Imports looks convenient, it has several obvious problems that lead to its gradual elimination:
- The loading method is not flexible enough : HTML Imports is loaded synchronously, which can easily cause page blockage and affect performance.
- No native module system support : After the ES6 module standard appeared, JavaScript has an official modular solution, which is more powerful and more general than HTML Imports.
- Web Components Development Direction Changes : Today's Web Components recommends using JavaScript classes to combine ES Modules to define components instead of relying on HTML file imports.
- Mainstream frameworks are turning to JS modular solutions : React, Vue, Angular and other mainstream frameworks are all built on JavaScript module systems, and HTML Imports gradually loses ecological support.
What are the alternatives?
If you used to organize components or templates with HTML Imports, there are several better alternatives now:
Using ES Modules to introduce JavaScript components
<script type="module" src="my-component.js"></script>
-
Create Web Components in combination with Shadow DOM and Custom Elements
Define the component class directly in JS and register it through
customElements.define()
. -
Front-end building tool module packer (such as Webpack, Vite)
HTML templates can be introduced as strings, or the framework's own component system can be used to manage the UI structure.
Basically that's it. HTML Imports once paved the way for the development of web components, but as technology evolves, it has fulfilled its historical mission. It is now more recommended to use a modular development method based on JavaScript, which is not only more compatible, but also easier to maintain and expand.
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