HTML form elements to JSON

html_form_to_json.js

// developer: RamOnRails.in
// purpose: fetch form data as JSON
// parameters:
//    form: the form object
//    arg: [optional] query selector to pick elements
// defaults: arg: "input, select, textarea"
function toJSON(form, arg = null) {
  // we will capture the elements and their values in this object
  let hash = {};
  // arg converted to string
  // default elements string concatenated with arg string (duplicates do not matter)
  // all specified elements selected from the `form`
  // ES6 spread operator used to make an array of the selected elements (we need array, not collection of objects)
  // elements array collection all selected
  const elements = [...form.querySelectorAll('input, select, textarea, ' + String(arg))];
  // `map` will loop through each element and run the function on each
  // we are adding every element into the `hash` we declared & defined above
  elements.map((element) => { hash[element.name] = element.value; });
  // converting object to JSON string
  // return the JSON string
  return JSON.stringify(hash);
}