JavaScriptOptimizerBlockedForSites

Block JavaScript optimizations on these sites

Supported versions

  • Windows: ≥ 134
  • macOS: ≥ 134
  • Android: ≥ 138
  • iOS: Not supported

Description

Allows you to set a list of site URL patterns that specify sites for which advanced JavaScript optimizations are disabled.

Disabling JavaScript optimizations means that Microsoft Edge may render web content more slowly.

For detailed information on valid URL patterns, see https://go.microsoft.com/fwlink/?linkid=2095322. Wildcards, *, are allowed.

You can set policy exceptions for specific subdomains and entire sites. For example, a policy set only for subdomain.contoso.com applies to subdomain.contoso.com without affecting contoso.com. In some cases, when a subdomain can't be isolated from its parent site, it may inherit the policy set on the parent site. Exceptions also may not take effect for frames loaded in an existing tab until the site is opened in a new tab. On low-memory Android devices, site-specific exceptions may not be enforced. Instead, sites use the policy from DefaultJavaScriptOptimizerSetting, if set, or default to the profile's JavaScript optimization setting.

To enforce exceptions, Microsoft Edge may place sites or subdomains with settings that differ from the default in dedicated processes. This behavior can increase memory usage, especially on Android devices or when a wildcard pattern matches many subdomains, because each matching origin may be isolated separately. Isolated subdomains also can't use document.domain to access their parent site.

Note: In version 138 and earlier, policy exceptions were enforced only at the site level (eTLD+1). A policy set only for subdomain.contoso.com didn't take effect, even for subdomain.contoso.com. The policy had to be set on contoso.com to apply to both contoso.com and subdomain.contoso.com.

This policy applies on a frame-by-frame basis and isn't based only on the top-level origin URL. For example, if contoso.com is listed in the JavaScriptOptimizerBlockedForSites policy, but contoso.com loads a frame that contains fabrikam.com, contoso.com has JavaScript optimizations disabled. However, fabrikam.com uses the policy from DefaultJavaScriptOptimizerSetting, if set, or defaults to JavaScript optimizations enabled. Blocklist entries have higher priority than allowlist entries, and allowlist entries have higher priority than the configured default value.

If you don't configure this policy for a site, the policy from DefaultJavaScriptOptimizerSetting applies to the site, if set. Otherwise, JavaScript optimization is enabled for the site.

Supported features

  • Can be mandatory: Yes
  • Can be recommended: No
  • Dynamic Policy Refresh: Yes
  • Per Profile: Yes
  • Applies to a profile that is signed in with a Microsoft account: No

Data type

  • List of strings

Windows information and settings

Group Policy (ADMX) info

  • GP unique name: JavaScriptOptimizerBlockedForSites
  • GP name: Block JavaScript optimizations on these sites
  • GP path (Mandatory): Administrative Templates/Microsoft Edge/Content settings
  • GP path (Recommended): N/A
  • GP ADMX file name: MSEdge.admx

Example value

[*.]example.edu

Registry settings

  • Path (Mandatory): SOFTWARE\Policies\Microsoft\Edge\JavaScriptOptimizerBlockedForSites
  • Path (Recommended): N/A
  • Value name: 1, 2, 3, ...
  • Value type: List of REG_SZ

Example registry value

SOFTWARE\Policies\Microsoft\Edge\JavaScriptOptimizerBlockedForSites\1 =

[*.]example.edu

Mac information and settings

  • Preference Key name: JavaScriptOptimizerBlockedForSites
  • Example value:
<array>
  <string>[*.]example.edu</string>
</array>

Android information and settings

  • Preference Key name: JavaScriptOptimizerBlockedForSites
  • Example value:
["[*.]example.edu"]

See also

  • Last updated on