Fetch api request with formdata

Hello everyone!,

After going through a couple of practice with fetch API sessions, I am trying to do a project of my own and need some assistance.

const postData = async (formdata) => {
  try {
    const response = await fetch('testphp.php',
      {
        method: 'POST',
        body: formdata
      });
    if (response.ok) {
      const data = await response.json()
      console.log(data);
    }
  } catch (e) {
    console.log(e);
  }
}

So I am able to see an array in console section of the browser and I am seeing this is working. However, could someone help or guide how to write a code that I can call this function totally outside the aysnc function and console only the first item in the array in which it returned?

i tired calling this function as below, i am seeing postData.then is not a function. Please help.

postData.then(value => {
  console.log(value);
})