> Making a custom form control with JavaScript is going to make life worse for a lot of people. Just don’t do it. The browser’s built-in controls are quite sufficient.

An extremely common use case at the last two companies I've worked at is a multi-select dropdown with autosuggest. Optionally, new items can be added to the list. Sometimes we needed to use ajax to populate the list, because you were searching 25,000+ items. We used this control in 10-15 different places, usually inside a spreadsheet cell. Which built-in controls should I use for this? I agree with the author that it is difficult to implement.