你可以试试这个

$("#target").prop("selectedIndex", 0);

你可以试试这个

$("#target").prop("selectedIndex", 0);

另一种重置值(对于多个选定元素)的方法是:

$("selector").each(function(){

    /*Perform any check and validation if needed for each item */

    /*Use "this" to handle the element in javascript or "$(this)" to handle the element with jquery */

    this.selectedIndex=0;

});

Use:

alert($( "#target option:first" ).text());

Use:

$("#selectbox option:first").val()

请在这个JSFiddle中找到工作简单。

// remove "selected" from any options that might already be selected
$('#target option[selected="selected"]').each(
    function() {
        $(this).removeAttr('selected');
    }
);


// mark the first option as selected
$("#target option:first").attr('selected','selected');