How to get each http body updates on angular Http request? - ajax

Question

I'm using an express api (my back-end) and an angular app (my front-end).
One express js end point (let's call it '/foo') is processing a lot of files,
i send data using res.write() after each treatment so the http response body is update.
I would like to get this update on my angular app.
I was using ajax in a previous version and it worked fine with ajax call :
xhrFields: {
// Getting on progress streaming response
onprogress: function(e)
{
var progressResponse;
var response = e.currentTarget.response;
if(lastResponseLength === false)
{
progressResponse = response;
lastResponseLength = response.length;
}
else
{
progressResponse = response.substring(lastResponseLength);
lastResponseLength = response.length;
}
actualResponse += progressResponse
}
Unfortunatly i found nothing to get partial http body. I tried to use 'reportProgress' Parameter but it's not working.
For some more context my front-end angular code:
service.ts :
setHolidaysDirectory(holidaysKey: string, path: string): Observable<Object>{
const setHolidayDirectoryStreamHttpRequest =
new HttpRequest('POST', 'http://localhost:8089/holidays/pictures/edit', { 'key': holidaysKey,
'path': path
}, {headers: this._httpHeaders, reportProgress: true, responseType: 'text'});
// pipe stream answer
return this._http.request(setHolidayDirectoryStreamHttpRequest);
}
and my component just call the service and subscribe :
this._holidaysService
.setHolidaysDirectory(key, finalHolidaysForm.path)
.subscribe((stream) => {
console.log('new answer');
console.log(stream);
}, error => console.log(error));
But unfortunatly i got empty answer and all the http body is recovered after res.end() (server side)
Can anyone help pls !
Thank a lot !