the event source polly could not fetch sse data but event source work

[jiangxiaoqiang]

I have defined a rust sse api:

use actix_web::{App, HttpResponse, HttpServer, Responder, post, get};
use rust_wheel::common::util::net::sse_stream::SseStream;
use std::time::{Duration, SystemTime};
use tokio::{
    sync::mpsc::{UnboundedReceiver, UnboundedSender},
    task,
};

#[get("/sse/producer")]
pub async fn sse() -> impl Responder {
    let (tx, rx): (UnboundedSender<SSEMessage>, UnboundedReceiver<SSEMessage>) =
        tokio::sync::mpsc::unbounded_channel();
    task::spawn(async move {
        for _ in 0..5 {
            let message:SSEMessage = SSEMessage::from_data(&"data11".to_string(),&"TEX_LOG".to_string());
            tx.send(message).unwrap();
            tokio::time::sleep(Duration::from_secs(1)).await;
        }
    });
    let response = HttpResponse::Ok()
        .content_type("text/event-stream")
        .streaming(SseStream { receiver: Some(rx) });
    response
}

#[actix_web::main]
async fn main() -> Result<(), std::io::Error> {
    HttpServer::new(|| App::new().service(sse).service(sse))
        .bind("127.0.0.1:8000")?
        .run()
        .await
}

and this is my cargo.toml:

[package]
name = "rust-learn"
version = "0.1.0"
edition = "2018"

[dependencies]
tokio = { version = "1.17.0", features = ["full"] }
serde = { version = "1.0.64", features = ["derive"] }
serde_json = "1.0.64"
actix-web = "4"
futures = "0.3"
eventsource = "0.5"
bytes = "1"
reqwest = { version = "0.11.20", features = ["stream"] }
tokio-stream = "0.1"
rust_wheel = { git = "https://github.com/jiangxiaoqiang/rust_wheel.git", branch = "diesel2.0" }
log4rs = "1.2.0"
log = "0.4.0"
actix-rt = "2.4.1"
futures-util = "0.3.28"

using this code to receive the data:

import React from 'react';
import { EventSourcePolyfill } from 'event-source-polyfill';

const App: React.FC = () => {

  React.useEffect(() => {
    doLocal();
  },[]);

  const doLocal = () => {
    let eventSource = new EventSourcePolyfill('/sse/producer');
    eventSource.onopen = () => {

    }
    eventSource.onerror = (error:any) => {
      console.log(error)
      eventSource.close();
    }
    eventSource.onmessage = (msg: any) => {
      console.log("origin polly:",msg)
    };
  }
}

export default App;

could not fetch any data but when I replace it with native event source like this:

const doOrigin = () => {
    let eventSource = new EventSource('/sse/producer');
    eventSource.onopen = () => {

    }
    eventSource.onerror = (error:any) => {
      console.log(error)
      eventSource.close();
    }
    eventSource.onmessage = (msg: any) => {
      console.log("origin:",msg)
    };
  }

it worked. why did this happen? Am I missing something?