


What are the integrity and crossorigin html attributes used for when loading scripts or styles from a CDN?
Jul 01, 2025 am 01:39 AMThe integrity attribute ensures a resource hasn’t been modified by using a cryptographic hash, while crossorigin handles cross-origin requests to enable proper validation. 1. Integrity checks the file’s authenticity via SHA-256, SHA-384, or SHA-512 hashes, blocking malicious or corrupted code if the hash doesn’t match. 2. Crossorigin enables CORS compatibility, typically set to anonymous for CDN scripts and styles. 3. Use both together when loading critical third-party assets to ensure security and reliability, updating hashes when versions change. 4. Gotchas include manual hash maintenance and testing after updates, though automation tools can help.
When you're loading scripts or styles from a CDN, using the integrity
and crossorigin
attributes helps improve security and reliability. These two attributes work together to ensure that the resource being loaded hasn’t been tampered with and that it’s fetched correctly across domains.

What is the integrity
attribute for?
The integrity
attribute is used to verify that the resource (like a JavaScript file or CSS stylesheet) delivered by the CDN hasn’t been modified. It uses a cryptographic hash of the file content to make sure what you’re loading matches exactly what you expect.

If the hash doesn't match — say, because someone tampered with the CDN or there was a network error — the browser won’t load the resource. This protects your site from loading malicious or corrupted code.
- Example usage:
<script src="https://cdn.example.net/example.js" integrity="sha384-oqVuAfXRKap7fdgcCY5uykM6 RrvGQRnNpKjzIVQwvLg==" crossorigin="anonymous"></script>
To use this, you need to generate a hash of the file in the correct format (usually SHA-256, SHA-384, or SHA-512). Tools like openssl
or online SRI (Subresource Integrity) generators can help with that.

Why do you need the crossorigin
attribute?
CDNs are often hosted on different domains, and browsers enforce CORS (Cross-Origin Resource Sharing) policies when fetching resources from them. The crossorigin
attribute tells the browser how to handle these cross-origin requests.
Even if you're not making API calls, scripts and stylesheets pulled from a CDN are still subject to CORS rules. Without setting crossorigin
, some browsers may not allow the browser to verify the integrity
hash properly.
Common values:
-
crossorigin="anonymous"
— sends a request without credentials (cookies, etc.), which is usually what you want. -
crossorigin="use-credentials"
— includes cookies and other auth info, but rarely needed for public CDNs.
Just remember: if you include an integrity
attribute, always add crossorigin="anonymous"
unless you have a specific reason not to.
When should you use both together?
You should use integrity
and crossorigin
together whenever you’re loading critical assets from third-party CDNs — especially for libraries like jQuery, Bootstrap, or React.
This combination gives you:
- Security via content verification (
integrity
) - Compatibility with CORS policies (
crossorigin
)
It’s especially useful for open-source projects or high-traffic sites where CDN trust is important. However, it’s worth noting that if the CDN changes the file even slightly (e.g., a new version), your hash will stop matching, and the resource won’t load. So keep your hashes updated when versions change.
A few gotchas and tips
- Generating and maintaining hashes manually can be tedious. Some build tools automate this process.
- Always test that your page still works after adding these attributes — especially after updating dependencies.
- If you host the files yourself (not using a CDN), you don’t strictly need these attributes, though they can still provide benefits.
That’s basically it — integrity
checks the file's authenticity, and crossorigin
makes sure the browser can fetch and validate it properly. Not super complex, but easy to overlook or misconfigure.
The above is the detailed content of What are the integrity and crossorigin html attributes used for when loading scripts or styles from a CDN?. For more information, please follow other related articles on the PHP Chinese website!

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