XHR2：js异步上传

http://dev.opera.com/articles/xhr2/

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var xhr = new XMLHttpRequest(); var onProgressHandler = function (event) { if (event.lengthComputable) { var howmuch = (event.loaded / event.total) * 100; document.querySelector( 'progress' ).value = Math.ceil(howmuch); } else { console.log( "Can't determine the size of the file." ); } } var onLoadHandler = function () { displayLoadedMessage(); } var onErrorHandler = function () { displayErrorMesssage(); } xhr.upload.addEventListener('progress ', onProgressHandler, false); xhr.upload.addEventListener(' load ', onLoadHandler, false); xhr.upload.addEventListener(' error ', onErrorHandler, false); var onReadyStateHandler = function(event) { if( event.target.readyState == 4 && event.target.status == 200){ } } xhr.open(' POST ',' /path_to_data'); xhr.onreadystatechange = onReadyStateHandler; xhr.send(dataToSend);