how to dynamically add options to an existing select in vanilla javascript

Question

I'd like to add option to a select dynamically using plain javascript. Everything I could find involves JQuery or tries to create the select dynamically as well. The closest thing I could find was Dynamically add input type select with options in Javascript which does the latter and was the only I found that doesn't involve JQuery. Although I did try and use it like so:

daySelect = document.getElementById('daySelect');
daySelect.innerHTML += "<option'>Hello world</option'>";
alert(daySelect.innerHTML)

After I did this there was no change to the select and the alert gave me

HELLO WORLD</option'>

I apologize if this is simple but I'm very new at javascript and web programming in general. Thank you for any assistance.

EDIT: So I tried the given suggestions like so.

daySelect = document.getElementById('daySelect');
myOption = document.createElement("option");
myOption.text = "Hello World";
myOption.value = "Hello World";
daySelect.appendChild(myOption);

This has not changed the select in the page at all. Any idea why? And I did check that the code was being run with an alert.

EDIT: The idea did work, it just turned out that it wasn't displaying a value in the dropdown. I don't know why but I can figure that one out I think.

Answer 1

This tutorial shows exactly what you need to do: Add options to an HTML select box with javascript

Basically:

 daySelect = document.getElementById('daySelect');
 daySelect.options[daySelect.options.length] = new Option('Text 1', 'Value1');