Rust Webview JavaScript interface

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I am developing a Web plug-in of Rust native app (Plug-in will be loaded into a Webview instance of native Rust app). My plug-in must fetch ( via GET/POST/PUT/DELETE requests) data from remote servers. Currently, my Web plug-in could not use default JavaScript fetch due to blocking by CORS errors. Therefore, I must find a way to call fetch handlers from Rust native app. 

I know that Android apps can expose JavaScript interface APIs to web plugins (run inside a Webview).

I would like to ask: How can Rust native apps expose JavaScript interface APIs to web plugins (run inside a Webview)" ?