Drop-down box dependent on the option selected in another drop-down box

Solution 1:

Try something like this... jsfiddle demo

HTML

<!-- Source: -->
<select id="source" name="source">
     <option>MANUAL</option>
     <option>ONLINE</option>
</select>

<!-- Status: -->
<select id="status" name="status">
    <option>OPEN</option>
    <option>DELIVERED</option>
</select>

JS

$(document).on('ready', function () {

    $("#source").on('change', function () {
        var el = $(this);
        if (el.val() === "ONLINE") {
            $("#status").append("<option>SHIPPED</option>");
        } else if (el.val() === "MANUAL") {
            $("#status option:last-child").remove();
        }
    });

});

Solution 2:

I am posting this answer because in this way you will never need any plugin like jQuery and any other, This has the solution by simple javascript.

<html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <script language="javascript" type="text/javascript">
    function dynamicdropdown(listindex)
    {
        switch (listindex)
        {
        case "manual" :
            document.getElementById("status").options[0]=new Option("Select status","");
            document.getElementById("status").options[1]=new Option("OPEN","open");
            document.getElementById("status").options[2]=new Option("DELIVERED","delivered");
            break;
        case "online" :
            document.getElementById("status").options[0]=new Option("Select status","");
            document.getElementById("status").options[1]=new Option("OPEN","open");
            document.getElementById("status").options[2]=new Option("DELIVERED","delivered");
            document.getElementById("status").options[3]=new Option("SHIPPED","shipped");
            break;
        }
        return true;
    }
    </script>
    </head>
    <title>Dynamic Drop Down List</title>
    <body>
    <div class="category_div" id="category_div">Source:
        <select id="source" name="source" onchange="javascript: dynamicdropdown(this.options[this.selectedIndex].value);">
        <option value="">Select source</option>
        <option value="manual">MANUAL</option>
        <option value="online">ONLINE</option>
        </select>
    </div>
    <div class="sub_category_div" id="sub_category_div">Status:
        <script type="text/javascript" language="JavaScript">
        document.write('<select name="status" id="status"><option value="">Select status</option></select>')
        </script>
        <noscript>
        <select id="status" name="status">
            <option value="open">OPEN</option>
            <option value="delivered">DELIVERED</option>
        </select>
        </noscript>
    </div>
    </body>
</html>

For more details, I mean to make dynamic and more dependency please take a look at my article create dynamic drop-down list

Solution 3:

    function dropdownlist(listindex)
    {
         document.getElementById("ddlCity").options.length = 0;
         switch (listindex) 
         {
             case "Karnataka":
                     document.getElementById("ddlCity").options[0] = new Option("--select--", "");
                     document.getElementById("ddlCity").options[1] = new Option("Dharawad", "Dharawad");
                     document.getElementById("ddlCity").options[2] = new Option("Haveri", "Haveri");
                     document.getElementById("ddlCity").options[3] = new Option("Belgum", "Belgum");
                     document.getElementById("ddlCity").options[4] = new Option("Bijapur", "Bijapur");

                 break;

             case "Tamilnadu":
                 document.getElementById("ddlCity").options[0] = new Option("--select--", "");
                 document.getElementById("ddlCity").options[1] = new Option("dgdf", "dgdf");
                 document.getElementById("ddlCity").options[2] = new Option("gffd", "gffd");


                 break;
         }

    }

* State: --Select-- Karnataka Tamilnadu Andra pradesh Telngana

    <div>
        <p>

            <label id="lblCt">
            <span class="red">*</span>
                City:</label>
            <select id="ddlCity">
               <!-- <option>--Select--</option>
                <option value="1">Dharawad</option>
                <option value="2">Belgum</option>
                <option value="3">Bagalkot</option>
                <option value="4">Haveri</option>
                <option>Hydrabadh</option>
                <option>Vijat vada</option>-->
            </select>
            <label id="lblCity"></label>
        </p>
    </div>

Solution 4:

In this jsfiddle you'll find a solution I deviced. The idea is to have a selector pair in html and use (plain) javascript to filter the options in the dependent selector, based on the selected option of the first. For example:

<select id="continents">
 <option value = 0>All</option>   
 <option value = 1>Asia</option>
 <option value = 2>Europe</option>
 <option value = 3>Africa</option>
</select> 
<select id="selectcountries"></select>

Uses (in the jsFiddle)

 MAIN.createRelatedSelector
     ( document.querySelector('#continents')           // from select element
      ,document.querySelector('#selectcountries')      // to select element
      ,{                                               // values object 
        Asia: ['China','Japan','North Korea',
               'South Korea','India','Malaysia',
               'Uzbekistan'],
        Europe: ['France','Belgium','Spain','Netherlands','Sweden','Germany'],
        Africa: ['Mali','Namibia','Botswana','Zimbabwe','Burkina Faso','Burundi']
      }
      ,function(a,b){return a>b ? 1 : a<b ? -1 : 0;}   // sort method
 );

[Edit 2021] or use data-attributes, something like:

document.addEventListener("change", checkSelect);

function checkSelect(evt) {
  const origin = evt.target;

  if (origin.dataset.dependentSelector) {
    const selectedOptFrom = origin.querySelector("option:checked")
      .dataset.dependentOpt || "n/a";
    const addRemove = optData => (optData || "") === selectedOptFrom 
      ? "add" : "remove";
    document.querySelectorAll(`${origin.dataset.dependentSelector} option`)
      .forEach( opt => 
        opt.classList[addRemove(opt.dataset.fromDependent)]("display") );
  }
}
[data-from-dependent] {
  display: none;
}

[data-from-dependent].display {
  display: initial;
}
<select id="source" name="source" data-dependent-selector="#status">
  <option>MANUAL</option>
  <option data-dependent-opt="ONLINE">ONLINE</option>
  <option data-dependent-opt="UNKNOWN">UNKNOWN</option>
</select>

<select id="status" name="status">
  <option>OPEN</option>
  <option>DELIVERED</option>
  <option data-from-dependent="ONLINE">SHIPPED</option>
  <option data-from-dependent="UNKNOWN">SHOULD SELECT</option>
  <option data-from-dependent="UNKNOWN">MAYBE IN TRANSIT</option>
</select>