I have read following posts from Damian Edwards.
https://github.com/aspnet/Mvc/issues/1576
https://github.com/aspnet/Mvc/issues/1580
At the ScriptTagHelper, I'm not sure what I should enter on asp-fallback-test attribute? It's the same as for jQuery? window.jQuery? How do I find the correct JavaScript Expression? Can someone give me an example based on moment-withlocales.min.js? Thanks!
Is following example for the LinkTagHelper correct?
<link
rel="stylesheet"
href="https://cdn.jsdelivr.net/bootstrap.daterangepicker/2/daterangepicker.css"
asp-fallback-href="~/lib/bootstrap-daterangepicker/daterangepicker.css"
asp-fallback-test-class="daterangepicker"
asp-fallback-test-property="position"
asp-fallback-test-value="absolute"
/>
Michael.
<script src="//whatever.cdn.com/moment.js"
asp-fallback-src="lib/moment.js"
asp-fallback-test="window.moment">
The fallback test is some function in the js file that will be defined by the js script. If the function is undefined then it loads the fallback script.
来源：https://stackoverflow.com/questions/40626754/how-to-use-fallback-source-on-scripttaghelper-and-linktaghelper-correctly