asp-fallback-test-property is specific to the
link tag-helper. It's the name of a CSS property you want to be interrogated, with
asp-fallback-test-value being the value you expect it to have (see the previous answer I wrote for the specifics).
asp-fallback-test is specific to the
As an example of
asp-fallback-test, imagine the following
<script src="/some/cdn/to/jquery" asp-fallback-src="~/local/path/to/jquery" asp-fallback-test="window.jQuery"></script>
In this example, after the browser attempts to load the script from
/some/cdn/to/jquery, the tag-helper will check whether
window.jQuery is truthy. If it is, there's nothing more to do. If it isn't (the CDN script couldn't be downloaded), it will inject a
script tag for
Commonly used Script Tag Helper attributes
See Script Tag Helper for all the Script Tag Helper attributes, properties, and methods.
The script method defined in the primary script to use for the fallback test. For more information, see FallbackTestExpression.
The URL of a Script tag to fallback to in the case the primary one fails. For more information, see FallbackSrc.
Preferred address of the linked resource. The address is passed thought to the generated HTML in all cases.
The URL of a CSS stylesheet to fallback to in the case the primary URL fails.
The class name defined in the stylesheet to use for the fallback test. For more information, see FallbackTestClass.
The CSS property name to use for the fallback test. For more information, see FallbackTestProperty.
The CSS property value to use for the fallback test. For more information, see FallbackTestValue.