Is there any way to repopulate an Html Select's Options without firing the Change event (using jQuery)?

Question

I have multiple selects:

<select id="one">
  <option value="1">one</option>
  <option value="2">two</option>
  <option value="3">three</option>
</select>
<select id="two">
  <option value="1">one</option>
  <option value="2">two</option>
  <option value="3">three</option>
</select>

What I want is to select "one" from the first select, then have that option be removed from the second one. Then if you select "two" from the second one, I want that one removed from the first one.

Here's the JS I have currently:

$(function () {
    var $one = $("#one");
    var $two = $("#two");

    var selectOptions = [];
    $("select").each(function (index) {
        selectOptions[index] = [];
        for (var i = 0; i < this.options.length; i++) {
            selectOptions[index][i] = this.options[i];
        }
    });

    $one.change(function () {
        var selectedValue = $("option:selected", this).val();
        for (var i = 0; i < selectOptions[1].length; i++) {
            var exists = false;
            for (var x = 0; x < $two[0].options.length; x++) {
                if ($two[0].options[x].value == selectOptions[1][i].value)
                    exists = true;
            }
            if (!exists)
                $two.append(selectOptions[1][i]);
        }

        $("option[value='" + selectedValue + "']", $two).remove();
    });
    $two.change(function () {
        var selectedValue = $("option:selected", this).val();
        for (var i = 0; i < selectOptions[0].length; i++) {
            var exists = false;
            for (var x = 0; x < $one[0].options.length; x++) {
                if ($one[0].options[x].value == selectOptions[0][i].value)
                    exists = true;
            }
            if (!exists)
                $one.append(selectOptions[0][i]);
        }

        $("option[value='" + selectedValue + "']", $one).remove();
    });
});

But when the elements get repopulated, it fires the change event in the select whose options are changing. I tried just setting the disabled attribute on the option I want to remove, but that doesn't work with IE6.

Answer 1

I am not (currently) a user of jQuery, but I can tell you that you need to temporarily disconnect your event handler while you repopulate the items or, at the least, set a flag that you then test for and based on its value, handle the change.

Answer 2

Here's the final code that I ended up using, the flag (changeOnce) worked great, thanks @Jason.

$(function () {
    var $one = $("#one");
    var $two = $("#two");

    var selectOptions = [];
    $("select").each(function (index) {
        selectOptions[index] = [];
        for (var i = 0; i < this.options.length; i++) {
            selectOptions[index][i] = this.options[i];
        }
    });

    var changeOnce = false;
    $one.change(function () {
        if (changeOnce) return;
        changeOnce = true;
        var selectedValue = $("option:selected", this).val();
        filterSelect(selectedValue, $two, 1);
        changeOnce = false;
    });
    $two.change(function () {
        if (changeOnce) return;
        changeOnce = true;
        var selectedValue = $("option:selected", this).val();
        filterSelect(selectedValue, $one, 0);
        changeOnce = false;
    });

    function filterSelect(selectedValue, $selectToFilter, selectIndex) {
        for (var i = 0; i < selectOptions[selectIndex].length; i++) {
            var exists = false;
            for (var x = 0; x < $selectToFilter[0].options.length; x++) {
                if ($selectToFilter[0].options[x].value == selectOptions[selectIndex][i].value)
                    exists = true;
            }
            if (!exists)
                $selectToFilter.append(selectOptions[selectIndex][i]);
        }
        $("option[value='" + selectedValue + "']", $selectToFilter).remove();
        sortSelect($selectToFilter[0]);
    }

    function sortSelect(selectToSort) {
        var arrOptions = [];

        for (var i = 0; i < selectToSort.options.length; i++)  {
            arrOptions[i] = [];
            arrOptions[i][0] = selectToSort.options[i].value;
            arrOptions[i][1] = selectToSort.options[i].text;
            arrOptions[i][2] = selectToSort.options[i].selected;
        }

        arrOptions.sort();

        for (var i = 0; i < selectToSort.options.length; i++)  {
            selectToSort.options[i].value = arrOptions[i][0];
            selectToSort.options[i].text = arrOptions[i][1];
            selectToSort.options[i].selected = arrOptions[i][2];
        }
    }
});