A Firefox Web Extension

Dev-related logs.

Cache-related HTTP headers

ETag
Cache-Control
Expires
Last-Modified

Cache Busting

Cache busting is where we invalidate a cached file and force the browser to retrieve the file from the server.

Versioning

We could add a version number to the filename:

assets/js/app-v2.min.js

Fingerprinting

We could add a fingerprint based on the file contents:

assets/js/app-d41d8cd98f00b204e9800998ecf8427e.min.js

Append Query String

We could append a query string to the end of the filename:

assets/js/app.min.js?version=2

HTTP response can't be intercepted

Intercept HTTP requests

To intercept HTTP requests, use the webRequest API. This API enables you to add listeners for various stages of making an HTTP request. In the listeners, you can:
get access to request headers and bodies, and response headers
cancel and redirect requests
modify request and response headers

Browser's dev console can't show modified HTTP headers

Headers modified in webRequest.onHeadersReceived are not displayed in Netmonitor

How to log HTTP headers in Firefox

HTTP logging

Open a new tab and type in "about:networking" into the URL bar.
Go to the "Logging section"
Adjust the list of modules that you want to log:

Logging only HTTP request and response headers: Replace MOZ_LOG=nsHttp:5 with MOZ_LOG=nsHttp:3

HTTP traffic-sniffing and manipulation tool

Hoxy

Nginx

Nginx reverse proxy with code injection

Module ngx_http_addition_module

Openresty

lua-gumbo

if is 'html', then cache it with content. After that, determine if the page is sent with ngx.arg[2]

if ngx.var.ishtml == "true" then 

        local data, eof = ngx.arg[1], ngx.arg[2]
        ngx.var.content = ngx.var.content .. data
	if eof == true then
		....

rungix/Walidator