how to calculate age from date of birth in javascript?

how to calculate age from date of birth in javascript – Calculate age from date of birth to current date. In our day to day programming we often come across business logic that depends on the age of a person.

how to calculate age from date of birth in javascript

i am going to see how to calculate the age of a person using their birth date as input in JavaScript Example with demo.

calculate age from date of birth in javascript

age calculator javascript

function calculate_age(dob) { 
    var diff_ms = Date.now() - dob.getTime();
    var age_dt = new Date(diff_ms); 
  
    return Math.abs(age_dt.getUTCFullYear() - 1970);
}

console.log(calculate_age(new Date(1982, 11, 4)));

console.log(calculate_age(new Date(1962, 1, 1)));

Calculate age using JavaScript

Example 1: Predefined date input

<script>  
    var dob = new Date("06/24/2001");  
 
    var month_diff = Date.now() - dob.getTime();  
      
 
    var age_dt = new Date(month_diff);   
      
      
    var year = age_dt.getUTCFullYear();  
      

    var age = Math.abs(year - 1970);  
        
    document.write("Age of the date entered: " + age + " years");  
</script>  

Example 2: dynamic date input

index.html

<html>  
<head>  
<script>  
function ageCalculator() {  
    var memberIp = document.getElementById("DOB").value;  
    var dob = new Date(memberIp);  
    if(memberIp==null || memberIp=='') {  
      document.getElementById("message").innerHTML = "**Select a date please!";    
      return false;   
    } else {  
       
    var month_diff = Date.now() - dob.getTime();  
      
 
    var age_dt = new Date(month_diff);   
      
  
    var year = age_dt.getUTCFullYear();  
      

    var age = Math.abs(year - 1970);  
       
    return document.getElementById("result").innerHTML =    
             "Age is: " + age + " years. ";  
    }  
}  
</script>  
</head>  
<body>  
<center>  
<h2 style="color: 32A80F" 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:32A80F" id="result" align="center"></h3>   
</center>  
</body>  
</html>  

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