How does Ajax achieve the effect of a progress bar?

The client initiates an AJAX request:
$ ("#data_container"). Load (server_url,{start_query_id:some_query_id});
Requires the server side to constantly return the current progress data and return to the client, for example, the client is constantly showing: the current query user_id is 5, the user information is Blahblahblah ...
At first I thought it was very simple, ob_flush did not solve it:
for ($i =0; $i <100; $i + +) {
echo $i. "
";
Flush ();
Ob_flush ();
Sleep (2);
}
As a result, it was a long time before PHP was all output at once. Want to ask where this is wrong?
If this does not work, can only be loaded with an IFRAME, IFRAME embedded page through Ob_flush () to resolve the current query output, but theoretically the browser's loading bar will always be in the loop state, inappropriate.
The rest can only be used in Ajax each return to the data will be re-submitted again query_id form, the page to keep requesting the server, request time also increased significantly, also increased the server burden.
With WebSocket, for the moment not to discuss his browser poor compatibility, PHP is not born to dry websocket material bar.
Then, do not know what to do, there is a relatively simple and friendly way to deal with this problem?

Reply content:

The client initiates an AJAX request:
$ ("#data_container"). Load (server_url,{start_query_id:some_query_id});
Requires the server side to constantly return the current progress data and return to the client, for example, the client is constantly showing: the current query user_id is 5, the user information is Blahblahblah ...
At first I thought it was very simple, ob_flush did not solve it:
for ($i =0; $i <100; $i + +) {
echo $i. "
";
Flush ();
Ob_flush ();
Sleep (2);
}
As a result, it was a long time before PHP was all output at once. Want to ask where this is wrong?
If this does not work, can only be loaded with an IFRAME, IFRAME embedded page through Ob_flush () to resolve the current query output, but theoretically the browser's loading bar will always be in the loop state, inappropriate.
The rest can only be used in Ajax each return to the data will be re-submitted again query_id form, the page to keep requesting the server, request time also increased significantly, also increased the server burden.
With WebSocket, for the moment not to discuss his browser poor compatibility, PHP is not born to dry websocket material bar.
Then, do not know what to do, there is a relatively simple and friendly way to deal with this problem?

Ob_flush () and Ajax are not the kind of effects you might imagine.

IFRAME Inline page through Ob_flush () can achieve what you want, but have you say "Turn circle".
The front-end set timer, constantly sending AJAX requests, this is the current practice.

To optimize Ajax, you can check the Commet.
Also, it is recommended that you consider whether you really want to output all the information for each user in a large batch of time-consuming operations.

False progress bar algorithm
Completion progress bar is 100%
0 ~ 25%: Random increment 3% ~ 6% per second
25% ~ 65%: Random increment 0.1% ~ 3% per second
65% ~ 90%: Random increment 0.1% ~ 2% per second
90% ~ 99%: Fixed increment 0.5% per second

Until the request is complete, it grows directly to 100%.

Agree with the false progress bar method, we used to do so. Just make sure that after processing is 100% on the line, the middle speed love how to.

Upstairs says the fake progress is good.

