Comparing dates on Typescript / Angular 4

Question

I am trying to compare dated in typescript/angular 4. In my case, I assigned system date into a variable named 'today' and database date assigned into a variable named 'dateToBeCheckOut'. Then I compared dates using if statement, In my case I expected to get the bookings which having checkout date is less than(before) today's date. But I get unexpected result instead of getting the expected result. I attached my code bellow and expect someone's help for understanding why it happens.

Here is the code

for(let k = 0; k < this.bookingDetailsArrayRealObject.length; k++){
        let dateCheckOut = this.bookingDetailsArrayRealObject[k].package.chackout;
        let dateToBeCheckOut = new Date(dateCheckOut);
        let today = new Date(Date.parse(Date()));
        //let today_test = new Date();
        if(this.bookingDetailsArrayRealObject[k].status){
          if(dateToBeCheckOut.toDateString() < today.toDateString()){
            this.bookingIdsToBeUpdated.push(this.bookingDetailsArrayRealObject[k]._id);
            window.alert('true');
            console.log(today.toDateString());
            console.log(dateToBeCheckOut.toDateString());
            console.log(this.bookingDetailsArrayRealObject[k]);
          }
        }
      }

booking object from database

console result

In console result, the 3rd one is unexpected according to the if statement. Any suggestion would be appreciated.

You are changing your date formats to strings e.g. "Wed Jul 04 2018" and then trying to see if one is larger than the other ? This is incorrect. Keep the Date values so you can compare them, or convert them to timestamps so one will be larger than the other. https://stackoverflow.com/questions/9873197/convert-date-to-timestamp-in-javascript — Smiter, Jul 04 '18 at 16:25

score 5 · Accepted Answer · answered Jul 04 '18 at 16:23

You can compare date objects without casting them as strings. Try:

for(let k = 0; k < this.bookingDetailsArrayRealObject.length; k++){
        let dateCheckOut = this.bookingDetailsArrayRealObject[k].package.chackout;
        let dateToBeCheckOut = new Date(dateCheckOut);
        let today = new Date();
        //let today_test = new Date();
        if(this.bookingDetailsArrayRealObject[k].status){
          if(dateToBeCheckOut < today){
            this.bookingIdsToBeUpdated.push(this.bookingDetailsArrayRealObject[k]._id);
            window.alert('true');
            console.log(today.toDateString());
            console.log(dateToBeCheckOut.toDateString());
            console.log(this.bookingDetailsArrayRealObject[k]);
          }
        }
      }

score 1 · Answer 2 · answered Jul 04 '18 at 18:13

Just a guess, did you check the timezone of the date objects at runtime?

When i had to handle local (browser) date/time and database (server) date/times i very often had the problem of different timezones.

An example: The database sends a date (in UTC), in the format "20190621T00:00:00" (ISO-8601 conform but without timezone information) I transfered that information with Date("20190621T00:00:00") into a Date object.

Now the fun started, because my computer was NOT in the UTC Timezone but in +02:00. And "Date()" assumes the current timezone, if no timezone is delivered.

As a result, my Date-Object then represented the date/time "20190621T00:00:00+02:00". And that´s a bit different then "20190621T00:00:00+00:00" what may database wanted to give me.

So i had database log entries that came directly from the future :-)

Perhaps

let databaseDate = new Date(Date.UTC(sourceDate));
let localDate = new Date(Date.UTC());

could help you?

Warm regards

Comparing dates on Typescript / Angular 4

2 Answers2