<select id="location">
    <option value="loc1">Location 1</option>
    <option value="loc2">Location 2</option>
    <option value="loc3">Location 3</option>
    <option value="loc4">Location 4</option>
    <option value="loc5">Location 5</option>
    <option value="loc6">Location 6</option>
    <option value="loc7">Location 7</option>
</select>
<select id="second">
    <option value="OPT1">Option 1</option>
    <option value="OPT2">Option 2</option>
    <option value="OPT3">Option 3</option>
    <option value="OPT4">Option 4</option>
</select>
#second {
  display: none;
  margin: 5px 0 
}

#second.show {
  display: block;
}

.jasmine_html-reporter{
  margin-top: 15px;
}
var source = document.getElementById("location");
var target = document.getElementById("second");
var triggerValue = "loc5";

function toggleShowOnSelectedValue(evt) {
  var selectedValue = this[this.selectedIndex].value;
  if (selectedValue === triggerValue) {
    target.className = "show";
  } else {
    target.className = "";
  }
};

//source.onchange = toggleShowOnSelectedValue;

source.addEventListener("change", toggleShowOnSelectedValue, false);
Run Pen

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.4.1/jasmine.min.css

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.4.1/jasmine.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.4.1/jasmine-html.min.js
  3. https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.4.1/boot.min.js
  4. https://codepen.io/SitePoint/pen/mAbQpY