并发Ajax调用？

I need to call a particular PHP script on my server several times. As each call will take some time (e.g. about .5 seconds) and each call is independent of each other, I want to call the scripts concurrently. Right now, I have something like this:

$(document).ready(function() {

    $.ajax({
      url: 'main.php',
      method: 'POST',
      data: { foo: 'foo' },
      success: function(result) {
        console.log(result);
      }
    });

    $.ajax({
      url: 'main.php',
      method: 'POST',
      data: { bar: 'bar' },
      success: function(result) {
        console.log(result);
      }
    });

});

Instead of making these calls sequentially, I want to do them concurrently. How do I do that?

Set your async = true on your AJAX calls to make them asynchronous.

$.ajax({
    async: "true",
      url: 'main.php',
      method: 'POST',
      data: { foo: 'foo' },
      success: function(result) {
        console.log(result);
      }
    });

    $.ajax({
    async: "true",
      url: 'main.php',
      method: 'POST',
      data: { bar: 'bar' },
      success: function(result) {
        console.log(result);
      }
    });

Ajax requests are asynchronous by nature. Based on your example, each of the calls will be dispatched without waiting for the server's response

Not sure what issue you are experiencing but you are making concurrent AJAX calls because jQuery defaults to async: true. If it defaulted to false then it would be called SJAX lol

One issue which you might be experiencing would be a session handling lockup.

If main.php is using session_start() then it will simply queue the bar request until foo finishes. Or you can manually call session_write_close() to avoid the lockup.