从javascript代码中调用Golang函数

I'm working on a webapp which already has a layout css, bootstrap v.3 along with an index.html. I have successfully loaded the project with Golang up and running. I have embedded a signup button which upon click is supposed to call a Go function from within the server.go file that handles http requests.

    $(document).ready(function() {
    $('#signup').on('click', loginHandler);
});

I have a server.go file written like this:

package main

import (
    "net/http"

    "github.com/bmizerany/pat"
)

func init() {
    m := pat.New()

    m.Get("/signup", http.HandlerFunc(loginHandler))
    m.Get("/", http.HandlerFunc(rootHandler))
    http.Handle("/", m)
}

func rootHandler(w http.ResponseWriter, r *http.Request) {
    http.ServeFile(w, r, r.URL.Path[1:])
}

func loginHandler(w http.ResponseWriter, r *http.Request) {

}

So the question is upon click on an button instance with signup Id, how do I have to trigger the golang loginHandler function in server.go file? Any idea on this would be appreciated.

What you are looking for is called AJAX (Asynchronous Javascript And Xml). It is a JavaScript technology that allows you make asynchronous HTTP requests to get data from the servers. It seems that you are using jQuery, and using jQuery with AJAX, would look like this:

$.ajax({
  url: "http://www.example.com/signup",
  data: {username: "whatever"} //If the request needs any data 
}).done(function (data) {
  // Do whatever with returned data
});

if you want, you can use functions specifically for GET and POST:

$.get("url: "http://www.example.com/signup", function (data) {
  // Do whatever with the returned data
});

$.post("url: "http://www.example.com/signup", {username: "whatever"}, function (data) {
  // Do whatever with the returned data
});

AJAX can even be performed without jQuery:

var req = new XMLHTTPRequest();
req.addEventListener("load", function (data) {// Do whatever});
req.open("get", "http://example.com", true);
req.send();

If you need a reference for AJAX, here are a few sites:

jQuery

https://api.jquery.com/jQuery.ajax/

https://api.jquery.com/category/ajax/shorthand-methods/

https://api.jquery.com/category/ajax/

Vanilla JavaScript

https://developer.mozilla.org/en-US/docs/AJAX/Getting_Started

https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Using_XMLHttpRequest