// Clears an input field when it is clicked on
// usage example:
// <input name="email" type="text" value="Enter email address" onfocus="prefillClear(this);" onblur="prefillClear(this);"/>

function prefillClear(field) {
	if (field.defaultValue==field.value) {field.value = '';}
	else if (field.value == '') {field.value = field.defaultValue;}
}