Ajax and ajax Technologies

Ajax and ajax Technologies

AJAX, that isASynchronousJAvascriptANdXMLAllows you to update the page without refreshing the status and submit the page asynchronously.

Advantages:

• No plug-in support
• Excellent User Experience
• Improve Web program performance
• Reducing the burden on servers and bandwidth

Disadvantages:

• The forward and backward buttons are damaged.
• Insufficient support for search engines
• Lack of development and debugging tools

Synchronous and asynchronous

• Synchronization: that is, you must do one thing, and wait for the previous one to finish before you can do the next thing.
• Asynchronous: you do not need to wait until the previous task is finished.

JQuery encapsulates AJAX in three layers

Bottom layer: encapsulates some basic Ajax operations;

• • Global Method: $. ajax ()
    • The submitted data is submitted in data and post. The submitted data must be wrapped in "{}" and submitted in the form of "key: value ".
    • When submitting the entire form, you can use form serialization "serialize ()" to submit the entire form.
    • DecodeURIComponent (): deserialized data
    • EncodeURIComponent (): serializes data. serialize () also calls this method for serialization.
    • SerializeArray (): converts a form to json format.
    • $. AjaxSetup (): initializes the data of $. ajax (), which is used to set the default value of the $. ajax () object.

Layer 2: encapsulates jQuery's Ajax;

• • Local method:. load (url, data, callback)
    • Suitable for asynchronous acquisition of static files
  • Global Method: $. get (url, data, callback, type), $. post (url, data, callback, type)
    • Can be obtained asynchronously with dynamic files

Layer 3: encapsulated get;

• • Global Method: $. getJSON, $. getScript

Load request

$ (Document). ajaxStart (function): Method triggered when a request starts.

$ (Document). ajaxStop (function): Method triggered when the request ends

JSON and JSONP

If dataType is JSON, data cannot be obtained across domains. Add "? Callback =. When dataType is JSONP, cross-domain data can be obtained directly.

JQXHR object

Attributes and methods of the jQuery jqXHR object