Detailed explanation of JS's Date object and obtaining the current time of the system_javascript skills

1. Date object
An object every day. Today let’s take a look at the Date object. You must be familiar with time, because it was used in many places on the website. Encountered such time effects. To review the past and learn something new, today we will recall the Date object.

Let’s first take a look at its definition:
dateObj = new Date()
dateObj = new Date(dateVal)
dateObj = new Date(year, month, date [, hours[, minutes[, seconds[,ms]]]])

Required. If a numeric value, dateVal represents the number of milliseconds in UTC between the specified date and midnight January 1, 1970. If it is a string, dateVal is parsed according to the rules in the parse method. The dateVal parameter can also be a VT_DATE value returned from some ActiveX® object. Required. The full year, for example, 1976 (not 76). Required. The month represented is an integer from 0 to 11 (January to December). Required. Represents a date as an integer from 1 to 31. Optional. Represents milliseconds as an integer from 0 to 999.
Date object holds a representation of a specific time period in milliseconds. If a parameter's value is greater than its range or negative, the other stored values ​​will be adjusted accordingly. For example, if you specify 150 seconds, JScript redefines the number to 2 minutes and 30 seconds.

If the number is NaN, the object does not represent a specific time period. If no arguments are passed to the Date object, it will be initialized to the current time (UTC). The object must be assigned a value before it can be used.

The date range that a Date object can represent is approximately 285,616 years before and after January 1, 1970.

The Date object has two static methods that can be called without creating a Date object. They are parse and UTC.

The Date object has many methods, which are very simple and will not be listed here. OK, See Next!

Special attention:

**************************************************** ***************

var myDate = new Date(2006,11,23);
alert("year=" myDate.getYear() "******month=" myDate.getMonth() "**** ****day=" myDate.getDate());

The result after running is year=2006 ******month=11************day=23

**************************************************** ***************

This display is normal. When the month passed in when new Date is 12, a problem occurs.

**************************************************** ***************

var myDate = new Date(2006,12,23);
alert("year=" myDate.getYear() "******month=" myDate.getMonth() "**** ****day=" myDate.getDate());

The result after running is year=2007 ******month=0************day=23

**************************************************** ***************

A very puzzling thing. Finally, after checking the information, I found that the value of the month parameter ranges from 0 to 11, and the value 12 cannot be passed in. The solution is to set month-1 when passing the value, and then add 1 when fetching it from outside. I don't know who has a better way.

For example:

var date=new Date(2010,0-1,15); //Here 0 represents January, subtract 1 to become December
alert(date.getYear() "," (date. getMonth() 1) "," date.getDate());

var date=new Date(2010,12-1,15);
alert(date.getYear() "," (date.getMonth() 1) "," date.getDate());

The parameter is in the format of a string, such as: 2010/1/6

Example:
var txtDepartureDate='2010-1-6'
alert(txtDepartureDate.replace(/-/g,'/')); //Use regular expressions to replace ' -'Replace all with /
var date = new Date(txtDepartureDate.replace(/-/g,'/'));