Add value to array in JSON file with createWriteStream node

I have a problem writing a json file using creatwritestream NodeJS. The JSON in file is ok But it append in the file, I need overwrite the content. I storing selected answer when clicked on button.

Example: Question A : Evaluated selected : D ANSWER (Save this in json) Question B: Evaluated selected : C ANSWER (Save this in json)

I GOT:

{"IdTest":"1021","answers":[{"questionID":"1","answerSelected":"D"}]}\n {"IdTest":"1021","answers":[{"questionID":"1","answerSelected":"D"},{"questionID":"2","answerSelected":"C"}]}

json file image

This is my code:

//init variables  
let jsonObject = {};
     const JSON_ANSWERS_FILE = fs.createWriteStream("path/to/jsons/file.json", {
        flags: 'w',
        encoding: 'utf8'
    });
    //I created the key and value for the json object
    jsonObject = {
             "id": 123,
             "answers": []
         }
    // BUTTON TO SAVE ANSWER IN JSON
     jsonObject.answers.push({
             "qID": $("#element").text(),
             "selected": $("input:radio[name=radioName]:checked").attr("value")
         })
    
         JSON_ANSWERS_FILE.write(JSON.stringify(jsonObject), (error) => {
             if (error) {
                 Swal.fire({
                     icon: 'error',
                     title: 'Oops...',
                     text: 'message'
                 })
             }
         })