Four ways to turn date into milliseconds

()

valueOf()
getTime() 

1. (): This method accepts a string parameter representing the date, and then tries to return the number of milliseconds of the date based on this date. ECMA-262 does not define which date format the method supports, so the behavior of this method varies by browser implementation. If the incoming string cannot represent the date, it returns NaN. The last three digits of the millisecond value returned by this method are all 0, which is accurate to the number of seconds, without the number of milliseconds.

("September 9, 2012") NaN   ("2012 9 9") 1347120000000   // Convert milliseconds to date format new Date(("2012 9 9")) Sun Sep 09 2012 00:00:00 GMT+0800 (China Standard Time)

2. (): This method also returns the number of milliseconds representing the date, but the parameters accepted by the method are year, month based on 0, which day of the month, hours, minutes, seconds, and milliseconds. Only the first two of these parameters are required.

(12) NaN   (2013,4,11); 1368230400000

3. valueOf(): This method returns the millisecond representation of the date, which can facilitate time comparison. The number of milliseconds returned by this method is accurate to milliseconds.

var date = new Date(); (); 1368283579633

4. getTime(): Returns the number of milliseconds representing the date, the same value returned by valueOf(), and is also accurate to the number of milliseconds.

var date = new Date(); (); 1368283691951