ios - Alternative for service-worker (background request) in iOS WKWebView < 14

Question

Since Service-workers are not supported in WkWebView in iOS < 14,

Sources:

1. http://openradar.appspot.com/51092505
2. https://webkit.org/blog/8090/workers-at-your-service/
3. Service workers unavailable in WKWebView

is there any alternative to implement background request functionality with javascript that works in iOS WkWebView < 14 ?