cos.getObjectUrl(
  {
    Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
    Region: 'COS_REGION', /* Bucket region (required), such as ap-beijing */
    Key: 'Profile photo.jpg', /* Object key stored in the bucket (required), such as `1.jpg` and `a/b/test.txt`. */
    Sign: true, /* Get a signed object URL. */
  },
  function (err, data) {
    if (err) return console.log(err);
    /* The URL is the object access URL. */
    var url = data.Url;
    /* Copy the value of `downloadUrl` to the browser and open it, and then download is automatically triggered. */
    var downloadUrl =
      data.Url +
      (data.Url.indexOf('?') > -1 ? '&' : '?') +
      'response-content-disposition=attachment'; // Add the parameter for a forced download
  }
);

function(err, data) { ... }