How can response header can be modified? - node.js

Question

i have a problem that break my mind since 2 days.
request( {url: url } , function(err,res, body){ res.headers['...'] = ...; return res }).pipe(response);
I thought this code change the header from the first response then put him on the second response. but NOT, all attempt fail. I try and I try but NOTHING, NOTHING WORKK.
Look, I'm really in peace and open-minded.
that's my code clear and concise :
modify_header(err,res,body){
var header = res.headers;
header['x-frame-options'] = null;
header['Set-Cookie'] = 'HttpOnly;';
return res;
}
request_src(req,response){
let isabsolute = this.decode_href(req.url);
if(!isabsolute) {
request.get({ url : this.url+req.url , headers : this.headers },this.modify_header).pipe(response);
}else{
request.get({ url : isabsolute , headers : this.headers },this.modify_header).pipe(response);
}
return false;
}
request_src(req,response) is a function called in http.createServer so, req & response are just the request from clients.
then, when i do request.get( {url:this.url ... I send client's request to an another site, like a proxy. but i need to change the header between the "other site" and the client. and believe me for sure, function modify_header modify nothing.
no, i lie just a little, when i set header['x-frame-options'] = null;res.headers is equals to null. that's ok
BUT, in the browser (client side) It just doesn't work that way. 'x-frame-options' is deny or something that's not mine (the same for cookie).
can you help me please, I pull out my hair since 2 days and this isn't good for me.
thank you.

Answer 1

The issue is that callbacks actually happen after a request is complete, which is way after the pipe has already begun streaming data to the response. You probably want to hook into the response event, which would look something like this:
request.get({ url: this.url + req.url, headers: this.headers })
.on('response', function (resp) {
resp.headers['my-custom-header'] = 'blah';
})
.pipe(response);
The response event is emitted before streaming to the destination (which in this case, is back to the original caller), so you should be able to do what you want using this method.

Answer 2

my code looks like that right now :
modify_header(res){
var header = res.headers;
header['x-frame-options'] = null;
header['Set-Cookie'] = 'HttpOnly;';
return res;
}
request_src(req,response){
console.log('original: ',req.url);
let isabsolute = this.decode_href(req.url);
if(!isabsolute) {
request.get({ url : this.url+req.url , headers : this.headers })
.on('response',this.modify_header)
.pipe(response);
}else{
request.get({ url : isabsolute , headers : this.headers})
.on('response',this.modify_header)
.pipe(response);
}
return false;
}