HTML Form: Select-Option vs Datalist-Option

From a technical point of view they're completely different. <datalist> is an abstract container of options for other elements. In your case you've used it with <input type="text" but you can also use it with ranges, colors, dates etc. http://demo.agektmr.com/datalist/

If using it with text input, as a type of autocomplete, then the question really is: Is it better to use a free-form text input, or a predetermined list of options? In that case I think the answer is a bit more obvious.

If we focus on the use of <datalist> as a list of options for a text field then here are some specific differences between that and a select box:

1. A <datalist> fed text box has a single string for both display label and submit. A select box can have a different submit value vs. display label <option value='ie'>Internet Explorer</option>.

2. A <datalist> fed text box does not support the <optgroup> tag to organize the display.

3. You can not restrict a user to the list of options in a <datalist> like you can with a <select>.

4. The onchange event works differently. On a <select> element, the onchange event is fired immediately upon change, whereas with <input type="text" the event is fired after the element loses focus or the user presses enter.

5. <datalist> has really spotty support across browsers. The way to show all available options is inconsistent, and things only get worse from there.

The last point is really the big one in my opinion. Since you will HAVE to have a more universal autocomplete fallback, then there is almost no reason to go through the trouble of configuring a <datalist>. Plus any decent autocomplete pluging will allow for ways to style the display of your options, which <datalist> does not do. If <datalist> accepted <li> elements that you could manipulate however you want, it would have been really great! But NO.

Also insofar as i can tell, the <datalist> search is an exact match from the beginning of the string. So if you had <option value="internet explorer"> and you searched for 'explorer' you would get no results. Most autocomplete plugins will search anywhere in the text.

I've only used <datalist> as a quick and lazy convenience helper for some internal pages where I know with a 100% certainty that the users have the latest Chrome or Firefox, and will not try to submit bogus values. For any other case, it's hard to recommend the use of <datalist> due to very poor browser support.

Think of it as the difference between a requirement and a suggestion. For the select element, the user is required to select one of the options you've given. For the datalist element, it is suggested that the user select one of the options you've given, but he can actually enter anything he wants in the input.

Edit 1: So which one you use depends upon your requirements. If the user must enter one of your choices, use the select element. If the use can enter whatever, use the datalist element.

Edit 2: Found this tidbit in the HTML Living Standard: "Each option element that is a descendant of the datalist element...represents a suggestion."