php - xmlhttprequest 在函数中不能正常工作

Question

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

代码正常运行(进度条缓慢移动):

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

但是如果我把它放到函数中，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;
    }
}   

在第二个代码中，进度条在文件上传完成后直接跳到100%，而不是在上传过程中很好地跳到100%

---

所以，我已经尝试了提供的解决方案，如果我将函数放入其中，它确实有效。有没有办法放到函数外面？

        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;
             }
        }   

Answer 1

使用 uploadProgress(event); 调用函数本身并将返回值分配给 xhr.upload.onprogress 而不是将其分配为回调函数:

xhr.upload.onprogress = uploadProgress;