|  | <!DOCTYPE html> | 
|  | <html> | 
|  | <head> | 
|  | <!-- This behaviour is not explicitly spelled out in the spec. | 
|  | It does say "queue tasks" under the "if the synchronous flag is unset" header in point 10 of the "send" algorithm.. --> | 
|  | <link rel="help" href="https://xhr.spec.whatwg.org/#the-send()-method" data-tested-assertations="following-sibling::ol/li[10]/dl/dd/dl/dd[2]/p[3]" /> | 
|  | <script src="/resources/testharness.js"></script> | 
|  | <script src="/resources/testharnessreport.js"></script> | 
|  | <title>XMLHttpRequest: sync requests should block events on pending async requests</title> | 
|  | </head> | 
|  |  | 
|  | <body> | 
|  | <div id="log"></div> | 
|  |  | 
|  | <script type="text/javascript"> | 
|  | var test = async_test(); | 
|  |  | 
|  | var expect = ['sync 4', 'async 2', 'async 3', 'async 4'] | 
|  | var actual = [] | 
|  |  | 
|  | test.step(function() | 
|  | { | 
|  | var xhr_async = new XMLHttpRequest() | 
|  | xhr_async.open('GET', 'resources/delay.py?ms=1000', true) // first launch an async request, completes in 1 second | 
|  | xhr_async.onreadystatechange = function() | 
|  | { | 
|  | test.step(function() | 
|  | { | 
|  | actual.push('async ' + xhr_async.readyState) | 
|  | if(xhr_async.readyState === 4 && actual.indexOf('sync 4')>-1){ | 
|  | VerifyResult() | 
|  | } | 
|  |  | 
|  | }); | 
|  | }; | 
|  | xhr_async.send() | 
|  |  | 
|  | setTimeout(function(){ | 
|  | var xhr_sync = new XMLHttpRequest(); | 
|  | xhr_sync.open('GET', 'resources/delay.py?ms=2000', false) // here's a sync request that will take 2 seconds to finish | 
|  | xhr_sync.onreadystatechange = function() | 
|  | { | 
|  | test.step(function() | 
|  | { | 
|  | actual.push('sync ' + xhr_sync.readyState) | 
|  | if(xhr_sync.readyState === 4 && actual.indexOf('async 4')>-1){ | 
|  | VerifyResult() | 
|  | } | 
|  | }); | 
|  | }; | 
|  | xhr_sync.send() | 
|  |  | 
|  | }, 10); | 
|  |  | 
|  | function VerifyResult() | 
|  | { | 
|  | test.step(function() | 
|  | { | 
|  | assert_array_equals(actual, expect); | 
|  | test.done(); | 
|  | }); | 
|  | }; | 
|  | }); | 
|  | </script> | 
|  | </body> | 
|  | </html> |