function configureDropDownLists(ddl1, ddl2) {

  var colours = ['Black', 'White', 'Blue'];

  var shapes = ['Square', 'Circle', 'Triangle'];

  var names = ['John', 'David', 'Sarah'];



  switch (ddl1.value) {

    case 'Colours':

      ddl2.options.length = 0;

      for (i = 0; i < colours.length; i++) {

        createOption(ddl2, colours[i], colours[i]);

      }

      break;

    case 'Shapes':

      ddl2.options.length = 0;

      for (i = 0; i < shapes.length; i++) {

        createOption(ddl2, shapes[i], shapes[i]);

      }

      break;

    case 'Names':

      ddl2.options.length = 0;

      for (i = 0; i < names.length; i++) {

        createOption(ddl2, names[i], names[i]);

      }

      break;

    default:

      ddl2.options.length = 0;

      break;

  }



}



function createOption(ddl, text, value) {

  var opt = document.createElement('option');

  opt.value = value;

  opt.text = text;

  ddl.options.add(opt);

}


<select id="ddl" onchange="configureDropDownLists(this,document.getElementById('ddl2'))">

  <option value=""></option>

  <option value="Colours">Colours</option>

  <option value="Shapes">Shapes</option>

  <option value="Names">Names</option>

</select>



<select id="ddl2">

</select>