Ajax status and readstatus

The readystate attribute has five possible values:
 
0: (not initialized) The send method has not been called
1: (loading) The send method has been called and the request is still being processed.
2: (loaded) The send method has been completed, and the entire response has been received
3: The response is being parsed.
4: (completed) the response has been resolved and is ready for further processing.

Object XMLHttpRequest

Description of attribute status:

0 **: not started

1 **: request received, continue processing

2 **: The operation is successfully received, analyzed, and accepted.

3 **: the request must be further processed.

4 **: The request contains an error syntax or cannot be completed

5 **: the server failed to execute a fully valid request.

100 -- the customer must continue to send the request

101 -- the client requests the server to convert the HTTP protocol version according to the request

200 -- transaction successful

201 -- prompt to know the URL of the new file

202 -- accept and process, but not complete

203 -- the returned information is uncertain or incomplete

204 -- the request is received, but the returned information is null.

205 -- when the server completes the request, the user agent must reset the file that has been browsed.

206 -- the server has completed some users' GET requests

300 -- the requested resources can be obtained in multiple places

301 -- Delete request data

302 -- request data found at other addresses

303 -- we recommend that you access other URLs or access methods.

304 -- the client has executed get, but the file has not changed

305 -- the requested resource must be obtained from the address specified by the server

306 -- used in the previous HTTP VersionCode, Which is not used in the current version

307 -- declaring temporary deletion of requested resources

400 -- incorrect request, such as syntax error

401 -- authorization request failed

402 -- retain valid chargeto header response

403 -- the request is not allowed

404 -- no file, query, or URL found

405 -- the method defined in the request-line field is not allowed.

406 -- the requested resource is inaccessible due to the user's accept drag.

407 -- similar to 401, the user must first be authorized on the Proxy Server

408 -- the client did not complete the request within the specified time

409 -- the request cannot be completed due to the current resource status

410 -- this resource is no longer available on the server and there is no further reference address

411 -- the server rejects the User-Defined Content-Length attribute request

412 -- one or more request header fields are incorrect in the current request

413 -- the requested resource is larger than the size allowed by the server

414 -- the requested resource URL is longer than the length allowed by the server

415 -- the requested resource does not support the format of the requested project

416 -- The request contains the range request header field, which has no range indication value in the current request resource range.

It does not contain the IF-range request header field.

417 -- the server does not meet the expectation specified by the request's CT header field. If it is a proxy server, it may be

The first-level server cannot meet the request

500 -- Internal error occurred on the server

501 -- the server does not support the requested function

502 -- the server is temporarily unavailable, sometimes to prevent system overload

503 -- server overload or service suspension

504 -- the gateway is overloaded. The server uses another gateway or service to respond to the user. The waiting time is long.

505 -- the server does not support or reject the specified HTTP version in the Request Header