CODEWITHSUNDEEP
javascript
dinesh hfghfghfh
dinesh hfghfghfh

Reputation: 11

date comparision in javascript

I have store date in dd-mm-yy like(21-05-2010) and I am getting system date by

var currentTime = new Date();
var month = currentTime.getMonth() + 1;
var day = currentTime.getDate();
var year = currentTime.getFullYear();.

So I have to compare this two values and have to find out which one is greater. I need to compare in Javascript function .so is their any function which compair this two values.

Upvotes: 1

Views: 199

Answers (4)

Patel Nikhil
Patel Nikhil

Reputation: 305

date11 = "2018-10-12";
date22 = "2018-12-02";

date1 = new Date(date11);
date2 = new Date(date22);

if(date1>date2){
    alert("date1>date2"); 
}
if(date1<date2){
    alert("date1<date2"); 
}
if(date2==date1){
    alert("date2==date1"); 
}

Upvotes: 1

Mateen
Mateen

Reputation: 1671

its simple if you get the date as an integer value of both the dates you compare and this can be done using "getTime()" method. This method returns the milliseconds from 1970 jan 1 to the date you give. Consider the following

 var fromDate = new Date();//current date
 var fromDateTime = fromDate.getTime();
 var toDate = new Date();
 toDate .setFullYear(2099,0,14);//changing for comparision
 var toDateTime = toDate.getTime();

 //MAIN LOGIC
 if(fromDateTime> toDateTime){
     alert('from time cannot be greater than to date');
     return false;
 }

Upvotes: 0

T.J. Crowder
T.J. Crowder

Reputation: 1073968

The JavaScript Date object can be used directly in relations, like <, >, <=, ==, etc., and also certain math operations (-, for instance). What happens under the covers is that the Date object's underlying primitive "time" value, which is milliseconds since The Epoch (the same value that you get from the getTime function), is used in the expression.

So:

var d1 = new Date(2010, 0, 1); // January 1st, 2010
var d2 = new Date(2010, 1, 1); // February 1st, 2010
display(d1 < d2); // alerts "true"
display(d1 > d2); // alerts "false"
display(d2 - d1); // alerts "2678400000", the difference in milliseconds

Live example

The above lines are functionally identical to:

var d1 = new Date(2010, 0, 1); // January 1st, 2010
var d2 = new Date(2010, 1, 1); // February 1st, 2010
display(d1.getTime() < d2.getTime()); // alerts "true"
display(d1.getTime() > d2.getTime()); // alerts "false"
display(d2.getTime() - d1.getTime()); // alerts "2678400000", the difference in milliseconds

This information is in the spec, but you really have to cross-reference sections to find it. We start with 11.8.5 ("The Abstract Relational Comparison Algorithm") that tells us the values will be compared using the [[ToPrimitive]] operation with the "hint" Number. Head over to section 9.1 ("ToPrimitive") and it tells us that for Objects, [[ToPrimitive]] just passes through to [[DefaultValue]], passing on the hint. Head over to 8.12.8 ("DefaultValue (hint)") and it tells us if the hint is Number and the object has a valueOf, it'll use valueOf. So check out Date's valueOf (15.9.5.8 ) and it says it returns "this time value" which is the spec's way of saying the number of milliseconds since The Epoch (read the introduction to the Date object [15.9.1, 15.9.1.1] to verify that). Conveniently, the very next section (15.9.5.9) is getTime, which says the same thing.

Whew!

(No, I didn't do all of that just to answer this question; I'd done it a year or so back when I realized I didn't quite know what was going on when I did this, and I got curious.)

Upvotes: 3

Mantar
Mantar

Reputation: 2720

var myDate=new Date();
myDate.setFullYear(2010,0,14);
var today = new Date();

if (myDate>today)
  {
  alert("Today is before 14th January 2010");
  }
else
  {
  alert("Today is after 14th January 2010");
  }

As seen here

http://wap.w3schools.com/js/js_obj_date.asp

Upvotes: 0

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