前端如何接收SSE流式数据传输（大模型网站常用）

使用fetchEventSource
参考：https://blog.csdn.net/qq_43750656/article/details/131591198
https://zhuanlan.zhihu.com/p/686618062

首先安装：

npm install --save @microsoft/fetch-event-source

我参考各个资料写的函数：

// 流式传输处理函数
export function sseRequest(url: string, data: object, successCallback: Function, closeCallback?: Function, errCallback?: Function) {
  const abortController = new AbortController()
  fetchEventSource(import.meta.env.VITE_APP_BASE_API + url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json;charset=utf-8',
      'Accept': '*/*',
      'token': localStorage.getItem('token')!
    },
    body: JSON.stringify(data),
    openWhenHidden: true, // 取消visibilityChange事件
    signal: abortController.signal, // AbortSignal
    // 按需添加此函数，不用就不添加
    async onopen(response) {
        if (response.ok && response.headers.get('content-type') === EventStreamContentType) {
            return; // everything's good
        } else if (response.status >= 400 && response.status < 500 && response.status !== 429) {
            // client-side errors are usually non-retriable:
            throw new FatalError();
        } else {
            throw new RetriableError();
        }
    },
    onmessage(ev) {
      // 每当消息推送过来时，就调用处理函数处理消息
      successCallback(ev)
    },
    one rror(err) {
      abortController.abort()
      if (errCallback) { errCallback(err) }
      throw err
    },
    onclose() {
      abortController.abort()
      if (closeCallback) { closeCallback() }
    }
  })
}

// 调用sseRequest示例：
export const beginWrite = (topic: string, styleId: string, style: string) => {
  const writeStore = useWriteStore()
  function successCallback(ev: { data: string, event: string, id: string, retry: number }) {
    if (ev.event === 'message') {
      const newStr = ev.data.replace(/_::_/g, '\n\n').replace(/_:_/g, '\n').replace(/_._/g, ' ')
      writeStore.sseInput += newStr
    }
    if (ev.event === 'message_end') {
      writeStore.sseInput = ''
    }
  }
  sseRequest('/knowledge/know_write', { topic, styleId, style }, successCallback)
}