Remove charset=utf-8 parameter from application/json content type

[MrPropre]

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Describe the bug

As per IANA notes on media types https://www.iana.org/assignments/media-types/application/json the charset parameter has no effect on the content type application/json.

A user reported that Chrome started throwing CORB (Cross-Origin-Read-Blocking) warnings when the content type was set to application/json; charset=utf-8

slimphp/Slim#2629 (comment)

Expected behavior

We need to remove ; charset=utf-8

The affected files are:

wp-rocket/assets/js/wpr-cpcss.js

Line 88 in 40ecc6c

xhttp.setRequestHeader( 'Content-Type', 'application/json;charset=UTF-8' );

wp-rocket/tests/Fixtures/content/htaccessContent.php

Line 11 in 4290c82

AddCharset UTF-8 .atom .css .js .json .rss .vtt .xml

wp-rocket/inc/functions/htaccess.php

Line 507 in 4290c82

$rules .= "AddCharset $charset .atom .css .js .json .rss .vtt .xml" . PHP_EOL;

Backlog Grooming (for WP Media dev team use only)

• Reproduce the problem
• Identify the root cause
• Scope a solution
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[Tabrisrp]

Hi @MrPropre,

Did you encounter the CORB warning when using the plugin?

[MrPropre]

Hello @Tabrisrp,

Not personally (I use Firefox) but I know that in most cases the warning can safely be ignored. Here is the documentation from Google: https://www.chromium.org/Home/chromium-security/corb-for-developers

A response served with a "X-Content-Type-Options: nosniff" response header and an incorrect "Content-Type" response header, may be blocked.

In most cases, the blocked response should not affect the web page's behavior and the CORB error message can be safely ignored.

It seems that adding ;charset=utf-8 to an application/json content type makes it incorrect due to Chrome's content type enhancement. Additionally, by checking IANA's site, we can see no charset parameter was ever actually defined in any RFC for the application/json type. It would be logical to remove it to stop the CORB warning on chrome, and to lighten the response size a bit.

Thank you.

[Tabrisrp]

Thank you for your feedback.

I'm thinking we can safely remove this from the code in wpr-cpcss.js.

I have more doubts for the .htaccess file directives, so I would not touch this one for now.

[Tabrisrp]

Scope a solution ✅

In assets/js/wpr-cpcss.js

• Remove the ;charset=UTF-8 on line 88

Estimate the effort ✅

Effort [XS]