It's a working draft, so it's normal if there are small differences or bugs in the implementations. I think Firefox still follows the behavior described in the draft of August 2011, where is specified that the exception is thrown if the state is not OPENED or HEADERS_RECEIVED.
這篇關于為什么在調用 open throw 之前設置 XMLHttpRequest responseType?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！
XMLHttpRequest cannot load, No #39;Access-Control-Allow-Origin#39; header is present on the requested resource(XMLHttpRequest 無法加載，請求的資源上不存在“Access-Control-Allow-Origin標頭) - IT屋-程序員軟件開發技術分
