HTTP & AJAX

Question 1

What is a client?

Answer 1

A service requester.

Question 2

What is a server?

Answer 2

A service provider.

Question 3

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

Answer 3

The GET method

Question 4

All HTTP requests and responses are composed of… (4)

Answer 4

1. A start-line describing the requests to be implemented, or its status of success / failure.
2. An optional set of HTTP headers specifying the request.
3. A blank line indicating all meta-information has been sent.
4. An option body containing data associated with the request or the document associated with the response.

Question 5

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

Answer 5

1. An HTTP method, a verb (GET, PUT, POST) or a noun (HEAD, OPTIONS) that describes the action to be performed.
2. The request target (often a URL) or the absolute path of the protocol port.
3. The HTTP version, which defines the structure of the remaining message.

Question 6

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

Answer 6

1. The protocol version (typically HTTP/1.1)
2. A status code — indicating success or failure of the request. (200, 404, or 302 most common)
3. A status text — brief purely information textual description of the status code.

Question 7

What are HTTP headers?

Answer 7

Headers let the client and server pass additional information within an HTTP request / response

Question 8

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

Answer 8

MDN

Question 9

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

Answer 9

Nope!

Question 10

What is AJAX?

Answer 10

A programming practice of building complex, dynamic webages using a techonolgy known as XMLHttpRequest

Question 11

What does the AJAX acronym stand for?

Answer 11

Asynchronous Javascript and XML

Question 12

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

Answer 12

XMLHttpRequest Object

Question 13

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

Answer 13

The load event.

Question 14

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

Answer 14

Via prototypical inheritance!

Question 15

What does fetch( ) return?

Answer 15

A pwomise.

Question 16

What is the default request method used by fetch( )?

Answer 16

GET

Question 17

How do you specify the request method (GET, POST, etc.) when calling fetch?

Answer 17

Fetch optionally accepts a second params, an init object (usually named req) —> add the ‘method’ property with the desired method (GET, POST, etc.) as the value.