How to hide a textbox based on a selected dropdown value

Add the following to the dropdown block:

Command: attribute

Value: onchange="hideBlock(this,'Name')";

Where ‘Name’ is the block name to hide

Add the following JS code to the Main Template

<script>
function hideBlock(obj,bname)
{
var col = $(obj).val();
var b = $("input[data-blockname='" + bname + "']");
if (col=="Blue") {
// Hide
b.val("");
b.parent().hide();
b.parent().siblings().hide();
}
else
{
// Show
b.parent().show();
b.parent().siblings().show();
        }  

    }

    // Runs when Page Loads
function _initLoad()
{
hideBlock($("select[data-blockname=Colour]"),"Name");
}
</script>

Where ‘Blue’ is the value when selected, block ‘Name’ will hide. The extra lines are there to hide the label as well.

Colour is the name of the Block to hide.