title: how get month from a string in javascript
body: <p>i have a date in string  like this: <code>var myDateStr='1431451872338.00';</code></p>
  
  <p>i want, getMonth() from this format date, i do:<code>var date = new Date(myDateStr);</code> but always return invalid date.</p>
  
  <p>and the method getMont() always return NaN, if I put this: <code>var date = new Date(1431451872338.00);</code> this return the date correct but with my string not</p>
  
  <p>my var myDateStr get the value from json and is variable, if  someone can help me thank you very much in advance, i hope do understand</p>