The first thing to do is to understand how we can modify the default HTTP headers for static files; as a matter of fact, we can do that by adding a custom set of options to the app.UseDefaultFiles() method call in the Startup.cs file that adds the StaticFiles middleware to the HTTP request pipeline.

In order to do that, open Startup.cs, scroll down to the Configure method, and replace that single line with the following code (new/modified lines are highlighted):

app.UseStaticFiles(new StaticFileOptions()
{
    OnPrepareResponse = (context) =>
    {
        // Disable caching for all static files. 
        context.Context.Response.Headers["Cache-Control"] = "no-cache,    
         no-store";
        context.Context.Response.Headers["Pragma"] = "no-cache";
        context.Context.Response.Headers["Expires"] = "-1";
    }
});

That wasn't hard at all; we just added some additional configuration values to the method call, wrapping them all within a dedicated StaticFileOptions object instance.

However, we're not done yet; now that we learned how to change the default behavior, we just need to change these static values with some convenient references pointing to the appsettings.Development.json file. To do that, we can add the following key/value section to the appsettings.Development.json file in the following way (new lines highlighted):

 {
  "Logging": {
    "IncludeScopes": false,
    "Debug": {
      "LogLevel": {
        "Default": "Debug",
        "System": "Information",
        "Microsoft": "Information"
      }
    },
    "Console": {
      "LogLevel": {
        "Default": "Debug",
        "System": "Information",
        "Microsoft": "Information"
      }
    }
  },
  "StaticFiles": {
    "Headers": {
      "Cache-Control": "no-cache, no-store",
      "Pragma": "no-cache",
      "Expires": "-1"
    }
  }
} 
 

Then, change the preceding Startup.cs code accordingly (modified lines highlighted):

 app.UseStaticFiles(new StaticFileOptions()
{
    OnPrepareResponse = (context) =>
    {
        // Disable caching for all static files. 
        context.Context.Response.Headers["Cache-Control"] = 
            Configuration["StaticFiles:Headers:Cache-Control"];
        context.Context.Response.Headers["Pragma"] = 
            Configuration["StaticFiles:Headers:Pragma"];
        context.Context.Response.Headers["Expires"] = 
            Configuration["StaticFiles:Headers:Expires"];
    }
});
 

Ensure that you add these values to the non-development version of the appsettings.json file as well, otherwise the application won't find them (when executed outside a development environment) and throw an error.

Since this will most likely happen in a production environment, we can take the chance to relax these caching policies a bit:

 {
  "Logging": {
    "IncludeScopes": false,
    "Debug": {
      "LogLevel": {
        "Default": "Warning"
      }
    },
    "Console": {
      "LogLevel": {
        "Default": "Warning"
      }
    }
  },
  "StaticFiles": {
    "Headers": {
      "Cache-Control": "max-age=3600",
      "Pragma": "cache",
      "Expires": null
    }
  }
}  

That's about it. Learning how to use this pattern is strongly advisable, as it's a great and effective way to properly configure our application's settings.