Javascript Serviceworker:处理和重新发送请求主体

我想使用Javascript服务工作者记录外发请求。我当前的方法是这样的:

self.addEventListener('fetch', function(event) {

    var req = new Request("https://example.com?url=" + encodeURI(event.request.url), {
        method: event.request.method,
        headers: event.request.headers,
        body: event.request.body
    });

    fetch(req);
});

This works fine for GET requests, but it doesn't work for the body of POST/PUT requests. I tried using body: event.request.body.blob(), but that did not work either.

是否有一种简单的方法可以访问服务工作者中的获取请求的主体并将其重新发送到其他地方?