vue - cannot convert submitEvent.target to formdata

update

I made a correct function based on the answer below

export function submitEvent_2_json(e) {
    const jsondata = {}
    let fd= new FormData(e.target)
    for (let key of fd.entries()) {
        jsondata[key[0]]=key[1]
    }
    return jsondata
}

origional problem

I'm trying to get data from form and convert it to json
It's obvious that data is in submitEvent.target(as follow picture), but the result is undefined or null

<template>
<form @submit.prevent="submit">
  <input id="aa"/>
  <button type="submit">ok</button>
</form>
</template>

<script setup>
function submit(e) {
  console.log(e)
  let fd= new FormData(e.target)
  console.log(fd)
  console.log(e.formData)
  console.log(fd.entries())
}
</script>

output