CODEWITHSUNDEEP
angulartypescriptsorting
Swoox
Swoox

Reputation: 3740

Sorting table on date with ''

So I have the following usecase where i have dates and empty strings in a table.

The problem is that the sorting doesn't do what I expected. Normally with strings it will put the empty string on the top or the bottom of the sort.

But with date it push them in between.

json = ['01-01-2018', '', '04-03-2018', '03-03-2018', '', '04-03-2018', '03-03-2018'];
this.json.sort((obj1: string, obj2: string) => {
  if (new Date(obj1) > new Date(obj2)) { return 1; }
  if (new Date(obj1) < new Date(obj2)) { return -1; }
  return 0;
});

This will result in: 01-01-2018,,03-03-2018,04-03-2018,,03-03-2018,04-03-2018.

Here is a simple stackblitz of it:

Stackblitz

I have tried to make it a number a sort it. But then still the issue with the empty string stays. Does any1 have a solution how to solve this?

Upvotes: 1

Views: 62

Answers (2)

Igor
Igor

Reputation: 62213

You need to check to see if the value is convertable to a date/time type and then return either -1 or 1 (depending on where you want them located) if they are not.

json = ['01-01-2018', '', '04-03-2018', '03-03-2018', '', '04-03-2018', '03-03-2018'];
this.json.sort((obj1: string, obj2: string) => {
  if (obj1 === obj2) { return 0; } // if they are the same then no need to convert these instances to Date types later, just return 0
  if (!obj1) { return 1; } // thruthy check
  if (!obj2) { return -1; } // thruthy check

  if (new Date(obj1) > new Date(obj2)) { return 1; }
  if (new Date(obj1) < new Date(obj2)) { return -1; }
  return 0;
});

stackblitz

// Initial array
'01-01-2018', '', '', '', '04-03-2018', '03-03-2018', '', '04-03-2018', '03-03-2018'

// Sorted array
'01-01-2018', '03-03-2018', '03-03-2018', '04-03-2018', '04-03-2018', '', '', '', ''

On a side note I recommend momentjs instead of javascript's Date. It is much more powerful and you can include a format string with the value you are passing in so the string is parsed correctly.

Upvotes: 1

Jens
Jens

Reputation: 69440

Check if the values are set:

 sort(){
    this.json.sort((obj1: string, obj2: string) => {
      if (!obj1 ||!obj2) {return -1}
      if (new Date(obj1)> new Date(obj2)) { return 1; }
      if (new Date(obj1)< new Date(obj2)) { return -1; }

      return 0;
    });
  }

result: 

,,01-01-2018,03-03-2018,03-03-2018,04-03-2018,04-03-2018

Upvotes: 0

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