问以下代码在click事件完成之前执行

EN

function filePost(ev) {
  var anch = getAnchor(ev);
  var form = document.querySelector(anch.dataset.form);
  var fileInput = form.querySelector('input[type="file"]');

  fileInput.click(); //<- CLICK EVENT I WANT TO WAIT FOR

  var url = form.getAttribute('action');
  var reloadTarget = anch.dataset.reload;
  var data = new FormData(form);
  var prom = fetch(url, {
    method: form.getAttribute('method'),
    credentials: 'same-origin',
    body: data
}).then(function (resp) {
    return resp.json();
}).then(function (response) {
    if (response.is_valid) {
        var html = response.html;
    } else {
        var html = response.err_msg;
    }
    document.querySelector(reloadTarget).innerHTML = html;
}).catch(function (err) {
    console.log(err);
});
return prom;
}