Show Date Picker Only if Default Choice is Empty

Hi,

Currently I am editing a survey. I have a question block where one of the fields is a question where users needs to enter the date. The question type is a Form field.

Sometimes, we create pre-filled links, so in that question, we used something like:

${e://Field/SomethingDate}

as the default choice. When we give the links, the URL will be like:

https://<Survey URL>/jfe/form/<Form ID>?SomethingDate=<Date>

I had entered a JavaScript to include a date picker using Pikaday+moment:

Qualtrics.SurveyEngine.addOnload(function()
{
	var inputId = 'QR~' + this.questionId;
	var picker = new Pikaday (
		{
			field: document.getElementById(inputId),
			firstDay: 1,
			maxDate: new Date(),
			format: 'YYYY/MM/DD',
			toString(date, format) {
        		var formattedDate = moment(date).format('MMM DD, YYYY');
				return formattedDate;
    		}
		}
	);

});

The date picker doesn’t show up in that question though.

The script does work if I add in a new question with a text entry type. How do I make the script behave for form field questions?