title: How to get the last day of the previous month in Javascript or JQuery
body: <p>I have the following code to get the current day: </p>
  
  <pre><code>var month=new Array(12);
  month[0]="January";
  month[1]="February";
  month[2]="March";
  month[3]="April";
  month[4]="May";
  month[5]="June";
  month[6]="July";
  month[7]="August";
  month[8]="September";
  month[9]="October";
  month[10]="November";
  month[11]="December";
  
  var d = new Date();
  var curr_date;
  if (d.getDate() == 1)
  {
      curr_date = d.getDate();
  }
  else
  {
      curr_date = d.getDate() - 1;
  }
  
  var curr_month = d.getMonth() + 1; //months are zero based
  var curr_year = d.getFullYear();
  var message_day = curr_year + "_" + curr_month + "_" + curr_date;
  var sql_day = month[curr_month - 1].substring(0,3) + curr_date.toString() + curr_year.toString();
  
  if (curr_date == "1")
      {
           document.write(sql_day + " " + message_day);
      }
  </code></pre>
  
  <p>This is great for getting the current day, but now i need to get the last day of the last month if it is the beginning of a new month.</p>
  
  <p>right now this will produce: </p>
  
  <pre><code>Feb12012 2012_2_1
  </code></pre>
  
  <p>but what i need output is:</p>
  
  <pre><code>Jan312012 2012_1_31
  </code></pre>
  
  <p>Thanks</p>