SH20RAJ/calculate-age-from-date-of-birth-with-birthday-alert.markdown

## calculate-age-from-date-of-birth-with-birthday-alert.markdown

      
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              calculate-age-from-date-of-birth-with-birthday-alert.markdown
            
          
    Calculate Age from Date of Birth with Birthday alert 🎂

A Pen by SH20RAJ on CodePen.
License.

  
## index.html
<html>
<head>
<script>

function ageCalculator() {
    //collect input from HTML form and convert into date format
    var userinput = document.getElementById("DOB").value;
    var dob = new Date(userinput);

    //check user provide input or not
    if(userinput==null || userinput==''){
      document.getElementById("message").innerHTML = "**Choose a date please!";
      return false;
    }

    //execute if user entered a date
    else {
    //extract and collect only date from date-time string
    var mdate = userinput.toString();
    var dobYear = parseInt(mdate.substring(0,4), 10);
    var dobMonth = parseInt(mdate.substring(5,7), 10);
    var dobDate = parseInt(mdate.substring(8,10), 10);

    //get the current date from system
    var today = new Date();
    //date string after broking
    var birthday = new Date(dobYear, dobMonth-1, dobDate);

    //calculate the difference of dates
    var diffInMillisecond = today.valueOf() - birthday.valueOf();

    //convert the difference in milliseconds and store in day and year variable
    var year_age = Math.floor(diffInMillisecond / 31536000000);
    var day_age = Math.floor((diffInMillisecond % 31536000000) / 86400000);

    //when birth date and month is same as today's date
    if ((today.getMonth() == birthday.getMonth()) && (today.getDate() == birthday.getDate())) {
            alert("Happy Birthday!");
        }

     var month_age = Math.floor(day_age/30);
     day_age = day_age % 30;

     var tMnt= (month_age + (year_age*12));
     var tDays =(tMnt*30) + day_age;

    //DOB is greater than today?s date, generate an error: Invalid date
     if (dob>today) {
        document.getElementById("result").innerHTML = ("Invalid date input - Please try again!");
      }
      else {
        document.getElementById("result").innerHTML = year_age + " years " + month_age + " months " + day_age + " days"
      }
   }
}
</script>
</head>
<body>
<center>
<h2 style="color: #008CBA" align="center"> Calculate Age from Date of Birth <br> <br> </h2>

<b> Enter Date of Birth: <input type=date id = DOB>  </b>
<span id = "message" style="color:red"> </span> <br><br>
<button type="submit" onclick = "ageCalculator()"> Calculate age </button> <br><br>
<h3 style="color:#008CBA" id="result" align="center"></h3>
</center>
</body>
</html>


## script.js
//Source :- https://www.javatpoint.com/calculate-age-using-javascript

//Create AgeCalculatorJS
	<html>
	<head>
	<script>

	function ageCalculator() {
	//collect input from HTML form and convert into date format
	var userinput = document.getElementById("DOB").value;
	var dob = new Date(userinput);

	//check user provide input or not
	if(userinput==null \|\| userinput==''){
	document.getElementById("message").innerHTML = "**Choose a date please!";
	return false;
	}

	//execute if user entered a date
	else {
	//extract and collect only date from date-time string
	var mdate = userinput.toString();
	var dobYear = parseInt(mdate.substring(0,4), 10);
	var dobMonth = parseInt(mdate.substring(5,7), 10);
	var dobDate = parseInt(mdate.substring(8,10), 10);

	//get the current date from system
	var today = new Date();
	//date string after broking
	var birthday = new Date(dobYear, dobMonth-1, dobDate);

	//calculate the difference of dates
	var diffInMillisecond = today.valueOf() - birthday.valueOf();

	//convert the difference in milliseconds and store in day and year variable
	var year_age = Math.floor(diffInMillisecond / 31536000000);
	var day_age = Math.floor((diffInMillisecond % 31536000000) / 86400000);

	//when birth date and month is same as today's date
	if ((today.getMonth() == birthday.getMonth()) && (today.getDate() == birthday.getDate())) {
	alert("Happy Birthday!");
	}

	var month_age = Math.floor(day_age/30);
	day_age = day_age % 30;

	var tMnt= (month_age + (year_age*12));
	var tDays =(tMnt*30) + day_age;

	//DOB is greater than today?s date, generate an error: Invalid date
	if (dob>today) {
	document.getElementById("result").innerHTML = ("Invalid date input - Please try again!");
	}
	else {
	document.getElementById("result").innerHTML = year_age + " years " + month_age + " months " + day_age + " days"
	}
	}
	}
	</script>
	</head>
	<body>
	<center>
	<h2 style="color: #008CBA" align="center"> Calculate Age from Date of Birth <br> <br> </h2>

	<b> Enter Date of Birth: <input type=date id = DOB> </b>
	<span id = "message" style="color:red"> </span> <br><br>
	<button type="submit" onclick = "ageCalculator()"> Calculate age </button> <br><br>
	<h3 style="color:#008CBA" id="result" align="center"></h3>
	</center>
	</body>
	</html>
	//Source :- https://www.javatpoint.com/calculate-age-using-javascript

	//Create AgeCalculatorJS