Bug 172627 – multiple files(5 files) upload with XMLHttpRequest(high cpu usage when listen to onprogress)

• Component: Accessibility
• Status: NEW

[baobao]

Here are the code sample:

var _createXDomainRequest = function(){
		var xhr = new XMLHttpRequest(); 
		//xhr.withCredentials = true;
		if(isIE9 && XDomainRequest){
			xhr = new XDomainRequest();
		}
		return xhr;
	};
var blobSlice = window.File && (File.prototype.slice || File.prototype.mozSlice || File.prototype.webkitSlice) || function(){};

var ajax = _createXDomainRequest();
ajax.onload = function(){};
ajax.onerror = function(){};
if(ajax.upload){
    ajax.upload.onprogress = function (event){}	
}
ajax.open('put', this.rangeData.upload_url, true);
ajax.setRequestHeader("Etag", md5);
ajax.setRequestHeader("Authorization", self.token);
ajax.send(blobSlice.call(self.blobFile, start, (end + 1)));


if i comment /*
if(ajax.upload){
    ajax.upload.onprogress = function (event){}	
}
*/
all the file upload are fine.

but I try to listen to onprogress, which cause high CPU usage.

[Radar WebKit Bug Importer]

<rdar://problem/32418707>