compresssion doesn't work ,the vue.txt is 2m

```js
app.use(
  compression({
    level: 6,
    filter: function(req, res) {
      return true;
    }
  })
);

router.get("/", function(req, res, next) {
  const fileData = fs.readFileSync("public/vue.txt").toString("base64");
  // res.setHeader("Content-Encoding", "zip");//it doesn't work
  res.json({
    fileData
  });
});
```