[1] Site Compatibility for Firefox 22 - Mozilla | MDN ( 版) https://developer.mozilla.org/en-US/Firefox/Releases/22/Site_compatibility#LSProgressEvent_has_been_removed

LSProgressEvent, an old interface which has been used especially with XMLHttpRequest and deprecated since Firefox 10, has been removed along with the input, position, totalSize attributes. As explained in the Monitoring progress section, the generic ProgressEvent interface can be used instead, including the loaded and total attributes.