Week 9 - Web Flashcards
(13 cards)
What does AJAX stand for?
asynchronous javascript and XML
describe ajax flow control
user event create promise or handler send XMLHTTPRequest server processes request send reply html/json/text response read by handler UI updated or other action performed
what does the XMLHTTPRequest permit?
parts of a web page to be updated
without reloading the whole page
What is AJAX?
Technique allowing clients to display active content requiring communication with server • without user having to reload page • not necessarily asynchronous • not necessarily XML
What does CORS stand for?
cross-origin resource sharing
What does CORS do?
adds HTTP headers which provide browsers with a way
to request remote URLs only if they have appropriate
permissions
— if a page loaded from one web server wants to access another it must request permission from the server by performing request
What does AJAX allow?
Ajax allows client-side code to interact with server
• request sent as HTTP GET or POST
• result string extracted from server response
What are the 2 styles of asynchronous code in jS?
callbacks
promises
What is a callback?
any executable code that is passed
as an argument to other code that is expected to call back
(execute) the argument at a given time.
What is a promise?
an object that is used as a placeholder for the
eventual results of a deferred (and possibly asynchronous)
computation.
What are a promises’ 3 fields?
- object that is promised
- a function that is used to resolve/fulfil promise
- a function that is used to reject the promise
what does it mean if a promise is pending?
neither fulfilled nor rejected
What is an asynchronous function?
a function which
executes asynchronously via the event loop, using
an implicit Promise to return its result.
