How to add options to select with JavaScript?

To add options to select with JavaScript, we use the Option constructor.

For instance, we add a select element with

<select id="ageSelect">
  <option value="">Please select</option>
</select>

Then we write

const selectElement = document.getElementById("ageSelect");

for (let age = 12; age <= 100; age++) {
  selectElement.add(new Option(age));
}

to select the select element with getElementById.

Then we use a for loop to loop through the age values and then create a new option element with the Option constructor called with its text content value.

Then we call selectElement.add to add the option as the last child of the select drop down.