What is Ajax? An interactive model of Ajax? What is the difference between synchronous and asynchronous? How do I troubleshoot cross-domain issues? and the HTTP status code

Source: Internet
Author: User

One. What Ajax is: 1. With asynchronous mode, the user experience is improved by 2. Optimizes the transfer between browser and server, reduces unnecessary data round-trip, and reduces bandwidth consumption by 3. Ajax runs on the client side, assuming some of the work that would otherwise have been done by the server, reducing the load on the server under a large user volume. The biggest features of  ajax: 1. Ajax can implement dynamic non-flush (partial refresh) 2. The ReadyState attribute state has 5 desirable values: 0 = uninitialized, 1 = start, 2 = send, 3 = receive, 4 = completion  ajax synchronous and Asynchronous differences: 1. Synchronization: Submit request, wait for server processing, processing finished return, this period client browser can not do anything 2. Asynchronous: Request through event triggering server processing (this is what the browser can still do)--and the 3rd parameter in the Ajax.open method is set to synchronous or asynchronous. Disadvantages of  ajax: 1. Ajax does not support browser Back button 2. Security issues Ajax exposes the details of the interaction with the server 3. Support for search engines is weaker by 4. Breaking the program's exception mechanism 5. Not easy to debug   troubleshoot cross-domain issues: 1. Jsonp2. Iframe3. Window.name, Window.postmessage4. Set Proxy page   two on the server. HTTP status Code Continue   continue, usually when the post request is sent, the HTTP header is sent after the server will return this information, indicating confirmation, and then send the specific parameter information, OK   Normal return information 201 Created & nbsp; the request was successful and the server created a new resource 202 Accepted   The server has accepted the request but has not processed 301 Moved permanently   requested page has been permanently moved to the new location 302 Found   Temporary REDIRECT 303 see other   temporary redirect, and always use GET to request new URI304 not Modified   The requested Web page has not been modified since the last request the request   Server does not understand the request Format, the client should not attempt to use the same content again to initiate the request 401 unauthorized   request unauthorized 403 Forbidden   Disable access 404 Not Found  Unable to find a resource that matches the URI. Internal Server error   Most common server-side errors 503 Service unavailable server side temporarily fails to process requests (may be overloaded or maintained)

What is

Ajax? An interactive model of Ajax? What is the difference between synchronous and asynchronous? How do I troubleshoot cross-domain issues? and the HTTP status code

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