如何检查所选选项的值是否高于另一个下拉列表中的值？

Question

So I have these two dropdown lists in html that look like this :

<SELECT name="obj_1" size="1" class="archive-select">
        <OPTION selected disabled>from</OPTION>
        <OPTION value="1">Less than 200</OPTION>
        <OPTION value="200">200</OPTION>
        <OPTION value="400">400</OPTION>
        <OPTION value="600">600</OPTION>
        <OPTION value="800">800</OPTION>
        <OPTION value="1000">1'000</OPTION>
        <OPTION value="1200">1'200</OPTION>
        <OPTION value="1400">1'400</OPTION>
        <OPTION value="1600">1'600</OPTION>
        <OPTION value="1800">1'800</OPTION>
        <OPTION value="2000">2'000</OPTION>
        <OPTION value="2200">2'200</OPTION>
        <OPTION value="2400">2'400</OPTION>
        <OPTION value="2600">2'600</OPTION>
        <OPTION value="2800">2'800</OPTION>
        <OPTION value="3000">3'000</OPTION>
    </SELECT><br>
    <SELECT name="obj_2" size="1" style="margin-bottom:15px;" class="archive-select">
        <OPTION selected disabled>to</OPTION>
        <OPTION value="200">200</OPTION>
        <OPTION value="400">400</OPTION>
        <OPTION value="600">600</OPTION>
        <OPTION value="800">800</OPTION>
        <OPTION value="1000">1'000</OPTION>
        <OPTION value="1200">1'200</OPTION>
        <OPTION value="1400">1'400</OPTION>
        <OPTION value="1600">1'600</OPTION>
        <OPTION value="1800">1'800</OPTION>
        <OPTION value="2000">2'000</OPTION>
        <OPTION value="2200">2'200</OPTION>
        <OPTION value="2400">2'400</OPTION>
        <OPTION value="2600">2'600</OPTION>
        <OPTION value="2800">2'800</OPTION>
        <OPTION value="3000">3'000</OPTION>
        <OPTION value="300000">More than 3'000</OPTION>
    </SELECT>

What I would like to do, is when the user selects in the first dropdown a certain number, to disable the ones that are of lower value in the second dropdown list. For example if I select 400, the options "Less than 200" and "200" should be disabled in the dropdown.

I kind of have the idea on how to work around this, but I just don't really know how I can check what the user chose and do my tests based on that. Any help is appreciated !

Answer 1

Try like this:

 var obj_1 = document.querySelector('select[name="obj_1"]'); var obj_2_options = document.querySelectorAll('select[name="obj_2"] option'); obj_1.onchange = function() { var val_1 = parseInt(obj_1.value.replace("'", "")); for (var i = 0; i < obj_2_options.length; i++) { var val_2 = parseInt(obj_2_options[i].value.replace("'", "")); obj_2_options[i].disabled = (val_2 < val_1); } }

 <SELECT name="obj_1" size="1" class="archive-select"> <OPTION selected disabled>from</OPTION> <OPTION value="1">Less than 200</OPTION> <OPTION value="200">200</OPTION> <OPTION value="400">400</OPTION> <OPTION value="600">600</OPTION> <OPTION value="800">800</OPTION> <OPTION value="1000">1'000</OPTION> <OPTION value="1200">1'200</OPTION> <OPTION value="1400">1'400</OPTION> <OPTION value="1600">1'600</OPTION> <OPTION value="1800">1'800</OPTION> <OPTION value="2000">2'000</OPTION> <OPTION value="2200">2'200</OPTION> <OPTION value="2400">2'400</OPTION> <OPTION value="2600">2'600</OPTION> <OPTION value="2800">2'800</OPTION> <OPTION value="3000">3'000</OPTION> </SELECT><br> <SELECT name="obj_2" size="1" style="margin-bottom:15px;" class="archive-select"> <OPTION selected disabled>to</OPTION> <OPTION value="200">200</OPTION> <OPTION value="400">400</OPTION> <OPTION value="600">600</OPTION> <OPTION value="800">800</OPTION> <OPTION value="1000">1'000</OPTION> <OPTION value="1200">1'200</OPTION> <OPTION value="1400">1'400</OPTION> <OPTION value="1600">1'600</OPTION> <OPTION value="1800">1'800</OPTION> <OPTION value="2000">2'000</OPTION> <OPTION value="2200">2'200</OPTION> <OPTION value="2400">2'400</OPTION> <OPTION value="2600">2'600</OPTION> <OPTION value="2800">2'800</OPTION> <OPTION value="3000">3'000</OPTION> <OPTION value="300000">More than 3'000</OPTION> </SELECT>

By looping through the option values for obj_2 , you can compare them to the value of obj_1 and disable them accordingly.

EDIT: In jQuery this would be:

 var obj_1 = $('select[name="obj_1"]'); var obj_2_options = $('select[name="obj_2"] option'); obj_1.on('change', function() { var val_1 = parseInt(obj_1.val().replace("'", "")); obj_2_options.each(function() { var val_2 = parseInt($(this).val().replace("'", "")); $(this).attr('disabled', (val_2 < val_1)); }); });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <SELECT name="obj_1" size="1" class="archive-select"> <OPTION selected disabled>from</OPTION> <OPTION value="1">Less than 200</OPTION> <OPTION value="200">200</OPTION> <OPTION value="400">400</OPTION> <OPTION value="600">600</OPTION> <OPTION value="800">800</OPTION> <OPTION value="1000">1'000</OPTION> <OPTION value="1200">1'200</OPTION> <OPTION value="1400">1'400</OPTION> <OPTION value="1600">1'600</OPTION> <OPTION value="1800">1'800</OPTION> <OPTION value="2000">2'000</OPTION> <OPTION value="2200">2'200</OPTION> <OPTION value="2400">2'400</OPTION> <OPTION value="2600">2'600</OPTION> <OPTION value="2800">2'800</OPTION> <OPTION value="3000">3'000</OPTION> </SELECT><br> <SELECT name="obj_2" size="1" style="margin-bottom:15px;" class="archive-select"> <OPTION selected disabled>to</OPTION> <OPTION value="200">200</OPTION> <OPTION value="400">400</OPTION> <OPTION value="600">600</OPTION> <OPTION value="800">800</OPTION> <OPTION value="1000">1'000</OPTION> <OPTION value="1200">1'200</OPTION> <OPTION value="1400">1'400</OPTION> <OPTION value="1600">1'600</OPTION> <OPTION value="1800">1'800</OPTION> <OPTION value="2000">2'000</OPTION> <OPTION value="2200">2'200</OPTION> <OPTION value="2400">2'400</OPTION> <OPTION value="2600">2'600</OPTION> <OPTION value="2800">2'800</OPTION> <OPTION value="3000">3'000</OPTION> <OPTION value="300000">More than 3'000</OPTION> </SELECT>