Is there a max number of options (values) in HTML

问题:

Does anyone know how many options a drop down list can have? Is it unlimited? How many before performance degrades?

回答1:

Does anyone know how many options a drop down list can have? Is it unlimited?

I imagine it is unlimited in theory, obviously not in practice as a computer's RAM and the specific browser's limitations come into play.

How many before performance degrades?

Again, this would depend on a few factors, at the least the specific browser, the computer's memory and processing power.

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EDIT: From experience, I have had drop down lists with thousands of options. It wasn't ideal though because who wants to scroll through all of those? This is why an auto-complete of some type is more desirable for numerous reasons, especially the end user's experience.

回答2:

Update: Based on DannyG, tested on Ubuntu with Firefox on a 4GB mem pc, limit was far beyond 10k tags. My current Firefox is set to use up to 3GB and it has reached a 100k options, but for that, you'd have to change the default config of the browser I guess.

We opted to use an Ajax autocomplete as replacement in all cases that 30+ options where given.

Both Firefox and Chrome limited to 10k options in Windows 64b with 4GB ram on default config.

Tested with JSFiddle http://jsfiddle.net/Mare6/

Html:

<a>Testing Select</a>
<select id="list"></select>

Javascript

window.onLoad = function() {
    for (var i=0; i<10000; i++) {
        var name = "Option "+i;
        var sel = document.getElementById("list");
        sel.options[sel.options.length] = new Option(name,i);
    }
});

Regards,

回答3:

I've used right around 500 in a list with no noticeable performance impact if that helps!

回答4:

In my experience the performance degradation is generally on the side of the user, my golden rule (learned somewhere) is seven options, give or take a few.

On a more SW related basis, probably the top range of Integer.

EDIT: BTW This is kind of relevant from Atwood

回答5:

Yes, the maximum for Chrome and Safari is 10000 items for select elements at least.

The relevant lines in the Chrome source can be found here: Defined max of 10000, Code that enforces limit and puts error in console

Firefox seems to have no practical limit from my testing.

回答6:

In theory, there is no limit, but some browsers will implement limits. (Similar to using document.write in an infinite loop.)

But, at the end of the day, the most I would ever recommend in a drop-down-list, is about 50, just because no-one wants to do that much scrolling. That said, if organized, say by alphabetical order, it may be appropriate to have as many as 200 items in a drop-down-list. (Like for a sign-up form where you must select you country of birth.)

Also, when you have many different set choices, a drop-down-list is normally the best option, regardless.