title: How to define and manipulate Date variable in JavaScript?
body: <p>I need to use the <code>Date</code> object for three different purposes, can I do this as follows?</p>
  
  <p>I am very new to JavaScript, so I am not sure if the following define is OK for all the browsers.</p>
  
  <pre><code>Date.prototype.yyyymmdd = function() 
  {
    var yyyy = this.getFullYear().toString();    
    var mm = (this.getMonth()+1).toString(); 
    var dd  = this.getDate().toString();    
    return yyyy+"-" + (mm[1]?mm:"0"+mm[0])+"-" + (dd[1]?dd:"0"+dd[0]); 
  
  }; 
  
  Date.prototype.mmddyyyy = function() 
  {
    var yyyy = this.getFullYear().toString();    
    var mm = (this.getMonth()+1).toString(); 
    var dd  = this.getDate().toString();    
  
    return (mm[1]?mm:"0"+mm[0])+"-" + (dd[1]?dd:"0"+dd[0])+"-" + yyyy; 
  }; 
  
  Date.prototype.mmdd = function() 
  {
     var yyyy = this.getFullYear().toString();    
     var mm = (this.getMonth()+1).toString(); 
     var dd  = this.getDate().toString();    
     return (mm[1]?mm:mm[0])+"/" + (dd[1]?dd:dd[0]);
  };
  
  
  var d0 = new Date();
  console.log(d0.mmddyyyy);
  
  var d1 = new Date();
  console.log(d1.yyyymmdd);
  
  var d2 = new Date();
  console.log(d2.mmdd);
  </code></pre>