Easy way to quick select a whole optgroup in select box

问题

I have a select box in which i can select multiple options. In the select box are multiple optgroups. Is there an easy way to select a whole optgroup at once in javascript?

回答1:

I suggest using jQuery (or another framework) to quickly handle DOM selections. Give each optgroup a class to make it easier to grab it.

$("optgroup.className").children().attr('selected','selected');

If you want to select the entire group based on the user selecting the group, do the following:

$("optgroup.className").select(function(e) {
  $(this).children().attr('selected','selected');
});

**Both examples are untested pseudo-code, but they should work with minimal changes, if necessary.

If you cannot use a framework, you'll have to traverse the DOM yourself to find the optgroup and children. You could attach a listener to the select element to grab the element being selected then traverse to the children that way, too.

回答2:

I'm normally against using jQuery for simple jobs like this but I can see its value here. Still, if you prefer a non-jQuery solution that will have the benefits of using no library, introducing no spurious ids or classes and running faster, here is one:

<script type="text/javascript">

function selectOptGroupOptions(optGroup, selected) {
    var options = optGroup.getElementsByTagName("option");
    for (var i = 0, len = options.length; i < len; i++) {
        options[i].selected = selected;
    }
}

function selectOptGroup(selectId, label, selected) {
    var selectElement = document.getElementById(selectId);
    var optGroups = selectElement.getElementsByTagName("optgroup");
    var i, len, optGroup;
    for (i = 0, len = optGroups.length; i < len; i++) {
        optGroup = optGroups[i];
        if (optGroup.label === label) {
            selectOptGroupOptions(optGroup, selected);
            return;
        }
    }
}

</select>

<select id="veg" multiple>
    <optgroup label="roots">
        <option>Swede</option>
        <option>Carrot</option>
        <option>Turnip</option>
    </optgroup>
    <optgroup label="leaves">
        <option>Spinach</option>
        <option>Kale</option>
    </optgroup>
</select>

<input type="button" onclick="selectOptGroup('veg', 'roots', true)" value="Select roots">

If your <optgroup> has an id you could do away with the selectOptGroup function and just pass the optgroup straight into selectOptGroupOptions.

回答3:

jquery:

$('#myoptgroup option').attr('selected', true);

回答4:

I was trying to do something similar just now.

I wanted to select an <optgroup>'s <option>s upon clicking the group's label. The first attempt went like this:

$('select > optgroup').click(function () {
    $(this).children().attr('selected', true);
});

This solution half worked...

Upon clicking the <optgroup>'s label all of its children became selected.

BUT when simply clicking an <option> it was still selecting all the other <option>s in the group! The problem was event bubbling, because the <option> is inside the <optgroup> technically you're clicking it too.

Therefore the final piece of the puzzle was to suppress the event bubbling upwards in the event that an <option> was actually clicked instead. The final solution then became:

$('select > optgroup').click(function () {
    $(this).children().attr('selected', true);
});

$('select > optgroup > option').click(function (e) {
    if (!e) var e = window.event;
    e.cancelBubble = true;
    if (e.stopPropagation) e.stopPropagation();
});

Job done!

EDIT

Infuriatingly this doesn't work work in IE8 (and doubtful < IE8 - maybe IE9?)...

It decides to totally ignore click events on both and elements. The only alternative that I can think of is to position elements above the optgroup labels to capture the click, but its probably not worth the effort...

来源：https://stackoverflow.com/questions/1473897/easy-way-to-quick-select-a-whole-optgroup-in-select-box

标签

javascript

html

optgroup