php – xmlhttprequest在函数中无法正常工作

有人知道为什么upload.onprogress如果在单独的函数上不能正常工作？

代码正常工作(进度条缓慢移动)：

        xhr.upload.onprogress = function(e) {
            if (e.lengthComputable) {
                progress.value = (e.loaded / e.total) * 100;
            }
        };  

但如果我把它投入使用,它就不再起作用了：

xhr.upload.onprogress = uploadProgress(event);

function uploadProgress(e) {
    if (e.lengthComputable) {
        progress.value = (e.loaded / e.total) * 100;
    }
}   

在第二个代码上,进度条在文件完成上传后直接跳转到100％而不是,在上传期间很好地移动到100％

所以,我已经尝试了所提供的解决方案,它实际上是有效的,如果我把功能放在里面.有没有办法把它放在功能之外？

        function uploadFile(blobFile, fileName) {
            ...
            ...

            // Listen to the upload progress for each upload.
            xhr.upload.onprogress = uploadProgress;

            // Progress Bar Calculation why it has to be in uploadFile function..
            function uploadProgress(e) {
                if (e.lengthComputable) {
                    progress.value = (e.loaded / e.total) * 100;
                }
            }                            

            uploaders.push(xhr);
            xhr.send(fd);
        }  

        //it does not work if I put it outside the function. is there anyway to do this?  
        function uploadProgress(e) {
             if (e.lengthComputable) {
                 progress.value = (e.loaded / e.total) * 100;
             }
        }   

解决方法:

使用uploadProgress(事件);您调用函数本身并将返回值赋给xhr.upload.onprogress,而不是将其指定为回调函数：

xhr.upload.onprogress = uploadProgress;