如何将API响应从后端（Go）传递到前端（React）？

Fairly new backend, specifically in Go. I'm finding it very hard to understand how backend can/should communicate to the frontend, especially in.

For example, I have a simple mock Books API in Go, which I'd like to pass the response from Go to React.

package main

import (...)

var books []Book

func main() {
    // initialize router
    r := mux.NewRouter()

    books = append(books, []Book{
        {
            ID: "1",
            Isbn: "23423",
            Title: "Book 1",
            Author: &Author{
                FirstName: "Nas",
                LastName: "Ahm",
            },
        },
        {
            ID: "2",
            Isbn: "97878",
            Title: "Book 2",
            Author: &Author{
                FirstName: "Has",
                LastName: "Ahm",
            },
        },
    }...)

    // router endpoints
    r.HandleFunc("/api/books", getBooks).Methods("GET")

    log.Fatal(http.ListenAndServe(":3000", r))

}

func getBooks(writer http.ResponseWriter, request *http.Request) {
    writer.Header().Set("Content-Type", "application/json")
    json.NewEncoder(writer).Encode(books)
}

So the question is, how do I pass the Books data to Frontend (react)?