Eloquent JavaScript, 4th Edition

18

HTTP AND FORMS

The HyperText Transfer Protocol, introduced in Chapter 13, is the mechanism through which data is requested and provided on the World Wide Web. This chapter describes the protocol in more detail and explains the way browser JavaScript has access to it.

The Protocol

If you type eloquentjavascript.net/18_http.html in your browser’s address bar, the browser first looks up the address of the server associated with eloquent javascript.net and tries to open a TCP connection to it on port 80, the default port for HTTP traffic. If the server exists and accepts the connection, the browser might send something like this:

GET /18_http.html HTTP/1.1
Host: eloquentjavascript.net
User-Agent: Your browser's name

Then the server responds, through ...