Help. Date validation with JavaScript

[Sergio45]

I am in the process of making a validation function for a date. I need help figuring out how to make it not accept the date entered if the date is not for 2 days in advanced. So if today's date is 10/30/2016 an error should show up saying that the date has to be 2 days from today's date. (11/01/2016).

I will post just the section with the function and go from there. 

Thanks in advanced. 

var $ = function(id) 
{	return document.getElementById(id);	}//end $
window.onload = function() 
{
	$("theForm").reset(); //Clear previous entries in FF
	
		$("btnSubmit").onclick = validateForm;
		$("btnReset").onclick = resetForm;
	
	
	
		$("currentTime").innerHTML = (new Date).toLocaleString();
	
	
	$("txtCustName").required = true;
	$("txtCustName").onblur = validateUserName;
	
	
	$("txtTitle").required = true;
	$("txtTitle").onblur = validateBookTitle;
	
	$("cmbFormat").onblur = validateBookFormat;
	$("cmbFormat").required = true;
	
	
	$("txtPrice").min = 10;
	$("txtPrice").max = 100;
	$("txtPrice").required = true;
	$("txtPrice").onblur=validateQuotedPrice;
	
	
	$("txtQuantity").required = true;
	$("txtQuantity").onblur=validateQuanityOrdered;
	
	$("rdoDiscover").onclick = hidePaymentOptionError;
	$("rdoPayPal").onclick = hidePaymentOptionError;
	$("rdoVisa").onclick = hidePaymentOptionError;
	
	$("rdoDiscover").required = true;
	$("rdoPayPal").required = true;
	$("rdoVisa").required = true;
	
	$("rdoDiscover").onblur=validatePaymentOption;
	$("rdoPayPal").onblur=validatePaymentOption;
	$("rdoVisa").onblur=validatePaymentOption;
	
	
	$("dtpDelivery").required = true;
	$("dtpDelivery").onblur=validateDate;
	$("dtpDelivery").max="2017-12-31";
	$("dtpDelivery").min="2016-01-01";
}




function validateDate()
{
	var ptr = $("dtpDelivery");  //Pointer to input field
	var err = $("errDelivery");  //Pointer to field's error marker

	err.style.visibility = "visible";
	
	//Regular Expression for yyyy-mm-dd
	//2016-11-26    2016-10-31
	var patternForYyyyMmDd = /^\d{4}-\d{2}-\d{2}$/;
	if(ptr.value=="")
	{
		var enteredDate = ptr.value.replace(/[-\.]/g, "/");;
		if(isDate(enteredDate))
		{
			//Before checking range, make sure date is the right format
			if(!enteredDate.match(patternForYyyyMmDd))
			{
				//Reformat it
				enteredDate = new Date(enteredDate).format("yyyy-mm-dd");
			}//end if
			if(enteredDate < ptr.min || enteredDate > ptr.max)
			{
				err.title = "Date must be between " + ptr.min + " and " + ptr.max + ".";
			} 
			else 
			{
				err.style.visibility = "hidden";
				ptr.value = enteredDate;
			}//end if out of range
		}
		else
		{
			err.title = "This is not a recognizable date.";
		}//end if isDate
	}
//	else 
//	{
		//Display error if required
//	} //end if missing
	
	return err.style.visibility=="hidden";
}//end validateDate

 

[TAHIRMIA]

I can't really help you as I don't know javascript but what sort of program are you trying to make

[Sergio45]

Actually it for an assignment I am working on. I have an Html file and an external JavaScript file. In the external Js File that is where I am building and calling the functions. I have other JS function files that I am "Importing" to use on the HTML page. If it helps I will upload what I have so far in a zip folder. Its ask for a name, book title, format, price, quantity, date,payment method, and total( still working on that also). 

Unit 10 - BookNook Validation (4).zip

[Mr_KoKa]

function validateDate(date){
	if(date.match(/^\d{4}-\d{2}-\d{2}$/)){
		var dateTime;
		if(!isNaN((dateTime = Date.parse(date + ' 00:00:00')))){
			var now = new Date();
			now.setHours(0);
			now.setMinutes(0);
			now.setSeconds(0);
			now.setMilliseconds(0);
			
			now = now.getTime();
			
			var minDiff = 1000 * 60 * 60 * 24 * 2;
			var diff = dateTime - now;
			
			if(diff >= minDiff){
				return true;
			} else {
				alert('Entered date has to be 2 days ahead current date.');
			}
		} else {
			alert('Wrong value.');
		}
	} else {
		alert('Wrong format.');
	}
	
	return false;
}

What I did is parse date from the input to check if it is valid, because 2016-99-99 will match patter but won't be valid date, parse returns NaN in such case.

Notice that I added time string, I noticed that without it my date end up ahead of value of timezone, so my timezine is GMT +2 and when i entered 2016-10-30 I ended up with timestamp for datetime of 2016-10-30 02:00:00

 

So when date is valid, parse returns timestamp with milliseconds, then I create new Date object that defaults to current datetime, I reset hours, minutes, seconds and milliseconds to compare just dates, then I convert Date object to timestamp by calling getTime method and finally I calculate difference between entered and current date and compare it with the minimal difference.

[Sergio45]

Thanks Mr_KoKa I will go ahead and do the adjustments. Appreciate the time . 

[protoCJ]

You can improve that code by passing the date you want to compare to as an argument, or even acceptable difference between them

function validateDate(dateToValidate, dateToCompareTo, difference) {
  ...
}
  
function daysToMiliseconds(days) {
  	return (24*60*60*1000)*days;
}

var isDateValid = validateDate('03/11/2016/', Date.now(), daysToMiliseconds(2));