如何更改请求标头（用户代理）中的客户端信息？

Question

我是使用MEAN-JS进行网络开发的新手，我试图创建多个iframe以针对不同的网络浏览器显示同一网站（例如，查看ie7和9之间的区别），因此我尝试编辑我的User-Agent字符串，但这不起作用。

Answer 1

There is no way to change the User-Agent header sent by the browser from client side code. The only way to achieve that would be to proxy the request through your server side code. You would also have to modify any JavaScript (returned by the site) that tests the User-Agent to override it.

However, changing the User-Agent header wouldn't show you what the website looks like in different browsers. While it might cause a site to return slightly different HTML/JS/CSS (but probably won't as not that many use user agent detection these days), IE7 and IE9 are different pieces of software and they interpret HTML/JS/CSS differently.

The only way to test how a site looks in IE7 is to actually open it in IE7.

Answer 2

Yes it is possible on the server side (the E,N in MEAN-JS), and easier using the request module , you just have to specify the user agent string in the option object inside a generic route to intercept any request from your website and test if it is a request for an image (bit file) or a plain text.
You can find the user agent string that you want in this link: User Agent String.Com
Like this:

app.get('*', function (req, res){
        req.headers["user-agent"] = ‘YOUR USER AGENT STRING’;
        var options = {
            url: req.path,
            headers: {'user-agent':req.headers['user-agent'],
                        'accept':req.headers.accept,
            }
        };
        if ( /image\//.test(req.headers.accept)){
            options.encoding= null;}
        request(options, function (error, response, body) {
            if (!error && response.statusCode == 200) {
                res.set(
            response.headers

            );
                res.send(body);

            }
            else {
                console.log('request error: ' + JSON.stringify(error));
                res.redirect('/');
            }
        });
    });