Javascript上传文件到阿里OSS存储，并支持进度查看

<input type="file" onchange="uploadMedia(this)">
<a id="showProgress" style="display:none;" href="#"></a>

function uploadMedia(_this) {
        var $this= _this;
        document.getElementById("showProgress").style.display="inline-block";

        var xhr = new XMLHttpRequest();

        //上传进度
        xhr.upload.addEventListener("progress", function(evt){
            //console.log(evt);
            if (evt.lengthComputable) {
                //上传中设置上传的百分比
                var percentComplete = Math.round(evt.loaded * 100 / evt.total);
                if (percentComplete == 100) {
                    setTimeout(function () {
                        document.getElementById("showProgress").innerHTML = '已上传'+percentComplete+"%";
                    }, 500)
                } else {
                    document.getElementById("showProgress").innerHTML = '已上传'+percentComplete+"%";
                }
            } else {
                document.getElementById("showProgress").innerHTML = '无法计算';
            }
        }, false);

        //请求完成后执行的操作
        xhr.addEventListener("load", function(evt){
            var message = evt.target.responseText;
                obj = eval("("+message+")");
            alert('上传成功，地址为：'+obj.data.filename)；
        }, false);

        //请求error
        xhr.addEventListener("error", uploadFailed, false);

        //请求中断
        xhr.addEventListener("abort", uploadCanceled, false);

        //参数转json
        var dataObj = JSON.parse(data);

        //设置请求参数
        var fd = new FormData();
        fd.append("OSSAccessKeyId", dataObj.OSSAccessKeyId);
        fd.append("Signature", dataObj.Signature);
        fd.append("callback", dataObj.callback);
        fd.append("expire", dataObj.expire);
        fd.append("key", dataObj.key);
        fd.append("name", $this.files[0].name);
        fd.append("policy", dataObj.policy);
        fd.append("file", $this.files[0]);

        //发送请求
        xhr.open("POST", 'https://'+dataObj.host);

        //发送数据
        xhr.send(fd);
    }

    function uploadFailed(evt) {
        alert("上传出错.");
    }

    function uploadCanceled(evt) {
        alert("上传已由用户或浏览器取消删除连接.");
    }

/**
* $object 为OSS上保存的文件路径和文件名，例如：media/2023/05/30/202305301747235055.mp4
*/
public function getUploadParams($object, $callbackUrl = '', $expire = 3600) {
        self::init();

        if(!$callbackUrl){
            $callbackUrl = self::$callbackUrl;
        }
        $callback_param = array(
            'callbackUrl' => $callbackUrl,
            'callbackBody' => 'filename=${object}&size=${size}&mimeType=${mimeType}&imageHeight=${imageInfo.height}&imageWidth=${imageInfo.width}',
            'callbackBodyType' => "application/x-www-form-urlencoded"
        );
        $callback_string = json_encode($callback_param);

        $base64_callback_body = base64_encode($callback_string);
        $now = time();
        $end = $now + $expire;
        $expiration = self::gmt_iso8601($end);

        //最大文件大小.用户可以自己设置
        $condition = array(0 => 'content-length-range', 1 => 0, 2 => 2684354560);//最大2.5G
        $conditions[] = $condition;

        //表示用户上传的数据,必须是以$dir开始, 不然上传会失败,这一步不是必须项,只是为了安全起见,防止用户通过policy上传到别人的目录
        $start = array(0 => 'eq', 1 => '$key', 2 => $object);
        $conditions[] = $start;
        $arr = array('expiration' => $expiration, 'conditions' => $conditions);
        //echo json_encode($arr);
        //return;
        $policy = json_encode($arr);
        $base64_policy = base64_encode($policy);
        $string_to_sign = $base64_policy;
        $signature = base64_encode(hash_hmac('sha1', $string_to_sign, self::$access_secret, true));

        $response = array();
        $response['host'] = self::$endpoint_bucket;
        $response['key'] = $object;
        $response['OSSAccessKeyId'] = self::$access_id;
        $response['policy'] = $base64_policy;
        $response['Signature'] = $signature;
        $response['expire'] = $end;
        $response['callback'] = $base64_callback_body;
        return json_encode($response);
    }

    public static function gmt_iso8601($time) {
        $dtStr = date("c", $time);
        $mydatetime = new DateTime($dtStr);
        $expiration = $mydatetime->format(DateTime::ISO8601);
        $pos = strpos($expiration, '+');
        $expiration = substr($expiration, 0, $pos);
        return $expiration . "Z";
    }