I try to update JSON file in backend with express and display new datas on frontend. But currently when I do request I get good response but data don't change.

Server Express (route) Script to edit JSON:

function editJSON(fr,en,es){
    var obj = {
        list_words: []
    }
    fs.readFile('./assets/words.json', 'utf-8', (err, jsonString) =>{
        if(err){
            console.log(err)
        }else {
            try{
                obj  = JSON.parse(jsonString)
                obj.list_words.push({fr: fr, en: en, es: es})
                json = JSON.stringify(obj)
                fs.writeFileSync('./assets/words.json',json,'utf-8',function (err){
                    if (err) throw err;
                    console.log('complete');
                })
            } catch (err){
                console.log(" Error parsing JSON", err)
            }

        }
    })
}

And below script to send data and other to display.

  methods: {
    async addWord () {
      var obj = {
        fr: this.words_input.fr,
        en: this.words_input.en,
        es: this.words_input.es
      }
      const res = await axios.post('http://localhost:3000/addwords', obj)
      const data = res.data
      console.log(data)
    }
  },
mounted: async function () {
    await axios.get('http://localhost:3000/words.json')
      .then(response => {
        this.words_init = response.data
      })
      .catch(error => {
        console.log('There was an error: ' + error.response)
      })
  }

If I restart server after request table with new data is displayed. If you know how I can display informations without restart server this can help me so much.

I tried this

 const res = await axios.post('http://localhost:3000/addwords', obj)
 const data = res.data.list_words
 this.words_init = data

With this route

app.post('/addwords',(req,res)=>{
    console.log(req.body.fr)
    const fr = req.body.fr
    const en = req.body.en
    const es = req.body.es
    editJSON(fr,en,es)
    console.log(fr)
    res.send(words)
    res.status(201).send('created User')
    res.end()
})

But I got error

"Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client"

From back

and

"[Vue warn]: Error in v-on handler (Promise/async): "Error: Request aborted"

From frontend

      const res = await axios.post('http://localhost:3000/addwords', obj)
      this.words_init = res.data.list_words
    ```
with this route everything work But mu new list don't display