How to use jQuery to select a dropdown option?

问题

I was wondering if it’s possible to get jQuery to select an <option>, say the 4th item, in a dropdown box?

<select>
    <option></option>
    <option></option>
    <option></option>
    <option></option>
    <option></option>
</select>

I want the user to click a link, then have the <select> box change its value, as if the user has selected it by clicking on the <option>.

回答1:

How about

$('select>option:eq(3)').attr('selected', true);

example at http://www.jsfiddle.net/gaby/CWvwn/

---

for modern versions of jquery you should use the .prop() instead of .attr()

$('select>option:eq(3)').prop('selected', true);

example at http://jsfiddle.net/gaby/CWvwn/1763/

回答2:

The solution:

$("#element-id").val('the value of the option');

回答3:

HTML select elements have a selectedIndex property that can be written to in order to select a particular option:

$('select').prop('selectedIndex', 3); // select 4th option

Using plain JavaScript this can be achieved by:

// use first select element
var el = document.getElementsByTagName('select')[0]; 
// assuming el is not null, select 4th option
el.selectedIndex = 3;

回答4:

I would do it this way

 $("#idElement").val('optionValue').trigger('change');

回答5:

The easiest way is val(value) function:

$('select').val(2);

And to get the selected value you give no arguments:

$('select').val();

Also, you if you have <option value="valueToSelect">...</option>, you can do:

$('select').val("valueToSelect");

DEMO

回答6:

if your options have a value, you can do this:

$('select').val("the-value-of-the-option-you-want-to-select");

'select' would be the id of your select or a class selector. or if there is just one select, you can use the tag as it is in the example.

回答7:

Use the following code if you want to select an option with a specific value:

$('select>option[value="' + value + '"]').prop('selected', true);

回答8:

I prefer nth-child() to eq() as it uses 1-based indexing rather than 0-based, which is slightly easier on my brain.

//selects the 2nd option
$('select>option:nth-child(2)').attr('selected', true);

回答9:

With '' element usually we use 'value' attribute. It will make it easier to set then:

$('select').val('option-value');

回答10:

Try this:

$('#mySelectElement option')[0].selected = true;

Regards!

回答11:

 Try with the below codes. All should work. 
    $('select').val(2);
    $('select').prop('selectedIndex', 1);
    $('select>option[value="5"]').prop('selected', true);
    $('select>option:eq(3)').attr('selected', 'selected');
    $("select option:contains(COMMERCIAL)").attr('selected', true);

回答12:

answer with id:

$('#selectBoxId').find('option:eq(0)').attr('selected', true);

回答13:

 $('select>option:eq(3)').attr('selected', 'selected');

One caveat here is if you have javascript watching for select/option's change event you need to add .trigger('change') so the code become.

 $('select>option:eq(3)').attr('selected', 'selected').trigger('change');

because only calling .attr('selected', 'selected') does not trigger the event

来源：https://stackoverflow.com/questions/4864620/how-to-use-jquery-to-select-a-dropdown-option