How can I set a javascript const to a value in a form element that could be either a dropdown select or a checked radio button?

I have an html form in a django site that is used for both add and update. If the form is for a new entry, I want the field estimateType to be radio buttons with three choices, one of which is checked by default. If the form is for an edit to an existing entry, I want the form widget to change to a select dropdown with additional choices to pick from.

In the javascript in the onchange event, I need to know what the value of the estimateType field is. I can get it to work for select, or radio input, but not both. For example, what I have right now is:

const estimateType = document.querySelector(input[name=estimateType]:checked).value;

That works for a radio button but not the select dropdown. How can I use the same const declaration but account for heterogeneous form input types?

Solution

You get the value of either a select element or radiolist by it's value property. There is no difference between the two.

Don't use a queryselector for this. In the case of the radio buttons, the queryselector will just get one of the elements, whereas form.estimateType is the collection aka. a radioList, and the radioList has the selected value.

document.addEventListener('click', e => {
  if (e.target.name == 'get_estimate_type') {
    let form = e.target.form;
    console.log(form.estimateType.value);
  }
});

<p>Form with select</p>
<form>
  <select name="estimateType">
    <option value="a">a</option>
    <option value="b" selected>b</option>
    <option value="c">c</option>
  </select>
  <button type="button" name="get_estimate_type">Get estimate type</button>
</form>
<p>Form with radio</p>
<form>
  <label><input type="radio" name="estimateType" value="a" checked>a</label>
  <label><input type="radio" name="estimateType" value="b">b</label>
  <button type="button" name="get_estimate_type">Get estimate type</button>
</form>