sigpad.js

	var signturePads = [];
    var studentSignaturePad = new SignaturePad(document.getElementById('student-signature-pad'), {
      backgroundColor: 'rgba(255, 255, 255, 0)',
      penColor: 'rgb(0, 0, 0)'
    });
    var saveButton = document.getElementById('submit');
    var cancelButton = document.getElementById('clear1');
	signturePads.push(studentSignaturePad);

	// saveButton.addEventListener("click", function (event) {
		function checksig(){

		for(var i in signturePads) {
			if (signturePads[i].isEmpty)
				alert("Please provide a student signature.");
		}