JS calculates the specified date plus how many days, plus how many months, plus how many years of the date

function DateAdd (interval,number,date) {/* * functionality: Implements VBScript's DATEADD functionality.   * Parameter: Interval, string expression representing the time interval to be added.   * Parameter: number, numeric expression that indicates how many time intervals to add.   * Parameters: Date, Time object.   * Returns: the new Time object.   * var now = new Date ();   * var newdate = DateAdd ("D", 5,now);                  *---------------DateAdd (interval,number,date)-----------------*/switch (interval) {                          Case "Y": {date.setfullyear (Date.getfullyear () +number);                          return date;                  Break                          } case "Q": {Date.setmonth (Date.getmonth () +number*3);                          return date;                  Break                          } case "M": {Date.setmonth (Date.getmonth () +number);                          return date;                  Break } case "W"  : {date.setdate (Date.getdate () +number*7);                          return date;                  Break                          } case "D": {Date.setdate (Date.getdate () +number);                          return date;                  Break                          } case "H": {date.sethours (date.gethours () +number);                          return date;                  Break                          } case "M": {date.setminutes (Date.getminutes () +number);                          return date;                  Break                          } case "S": {date.setseconds (Date.getseconds () +number);                          return date;                  Break } default: {date.SetDate (D.getdate () +number);                          return date;                  Break  }}} var now = new Date ();  Plus five days.  var newdate = DateAdd ("D", 5,now);  Alert (newdate.tolocaledatestring ())//plus two months.  Newdate = DateAdd ("M", 2,now);  Alert (newdate.tolocaledatestring ())//plus one year newdate = DateAdd ("y", 1,now); Alert (newdate.tolocaledatestring ())

　　

JS calculates the specified date plus how many days, plus how many months, plus how many years of the date