Convert jQuery serializeArray method function to vanilla javascript

I am using the jQuery serializeArray method to create an array of objects from a form, but the form already outputs an object. How would I rewrite this to vanilla JavaScript?

e.serializeArray().map(x=>{
  let cookie_val = Cookies.get(x.name)
    if (cookie_val && cookie_val != ''){
      e.find('input[name="'+x.name+'"]').val(cookie_val).change();
    }
})