Http

Question 1

What is a client?

Answer 1

service requesters, called clients

Question 2

What is a server?

Answer 2

the providers of a resource or service, called servers

Question 3

Which HTTP method does a browser issue to a web server when you visit a URL?

Answer 3

HTTP GET request
When a user wants to navigate to a page, the browser sends an HTTP GET request specifying the URL of its HTML page. The server retrieves the requested document from its file system and returns an HTTP response containing the document and an HTTP Response status code of “ 200 OK “ (indicating success).

Question 4

What three things are on the start-line of an HTTP request message?

Answer 4

1. An HTTP method, a verb (like GET, PUT or POST) or a noun (like HEAD or OPTIONS), that describes the action to be performed.
2. The request target, usually a URL, or the absolute path of the protocol, port, and domain are usually characterized by the request context.
3. The HTTP version, which defines the structure of the remaining message, acting as an indicator of the expected version to use for the response.

Question 5

What three things are on the start-line of an HTTP response message?

Answer 5

1. The protocol version, usually HTTP/1.1.
2. A status code, indicating success or failure of the request. Common status codes are 200, 404, or 302
3. A status text. A brief, purely informational, textual description of the status code to help a human understand the HTTP message.

Question 6

What are HTTP headers?

Answer 6

HTTP headers let the client and the server pass additional information with an HTTP request or response. An HTTP header consists of its case-insensitive name followed by a colon (:), then by its value. Whitespace before the value is ignored.

Question 7

Where would you go if you wanted to learn more about a specific HTTP Header?

Answer 7

MDN

Question 8

Is a body required for a valid HTTP request or response message?

Answer 8

Not all requests have one: requests fetching resources, like GET, HEAD, DELETE, or OPTIONS, usually don’t need one. Some requests send data to the server in order to update it: as often the case with POST requests (containing HTML form data).

Question 9

What is AJAX?

Answer 9

Ajax, which initially stood for Asynchronous JavaScript And XML, is a programming practice of building complex, dynamic webpages using a technology known as XMLHttpRequest.

Question 10

What does the AJAX acronym stand for?

Answer 10

Asynchronous JavaScript And XML,

Question 11

Which object is built into the browser for making HTTP requests in JavaScript?

Answer 11

To perform Ajax communication JavaScript uses a special object built into the browser—an XMLHttpRequest (XHR) object—to make HTTP requests to the server and receive data in response.

Question 12

What event is fired by XMLHttpRequest objects when they are finished loading the data from the server?

Answer 12

load

Question 13

Bonus Question: An XMLHttpRequest object has an addEventListener() method just like DOM elements. How is it possible that they both share this functionality?

Answer 13

they have a shared prototype object