How to add line break in Whatsapp text message using javascript?

$(document).on('click', '.btn-send-message', function(event){
	event.preventDefault();
	var mobileNumber = '+8801719316663';
	var messageString = "Hi, %0aI want to talk with you about my web or app development.%0aPlease help me!!";
	let openUrl = "whatsapp://send?text=" + messageString + "&phone=" + mobileNumber;
	window.open(openUrl, '_self');
});