CODEWITHSUNDEEP
javascriptdatedatetimethisself
dmvianna
dmvianna

Reputation: 15730

override Date prototype method

I have large arrays of dates in the client, and I want to send them in a JSON string to the server without a timezone, that is, I just want to send 2015-04-01 (the client local date) instead of 2015-03-31T16:00:00.000Z, which is the corresponding UTC date. The simplest way of achieving that seems to me to just override .toJSON.

My initial idea was to use datetime.js such as:

function toJSON(dt) {
    return datetime.strftime(dt, '%Y-%m-%d');
}

Date.prototype.toJSON = toJSON;

However, I don't know how to reference dt (the instance's self) to accomplish that.

Yes, I am thinking in Python still...

Upvotes: 0

Views: 2485

Answers (2)

RobG
RobG

Reputation: 147453

Maybe you need datetime.js for other things, but if you're just using if for this, you might consider a simple function (perhaps attached to Date.prototype or given a more meaningful name):

function toJSON(d) {
  
    // Helper for padding
    function pad(n, len) {
      return ('000' + n).slice(-len);
    }
    
    // If not called on a Date instance, or timevalue is NaN, return undefined
    if (isNaN(d) || Object.prototype.toString.call(d) != '[object Date]') return;
    
    // Otherwise, return an ISO format local date string
    return pad(d.getFullYear(), 4) + '-' +
           pad(d.getMonth() + 1, 2) + '-' +
           pad(d.getDate(), 2);
  }

  document.write(toJSON(new Date()));

Upvotes: 2

Arun P Johny
Arun P Johny

Reputation: 388416

Since toJSON is assigned as the prototype method, this will refer to the date inside the method so

function toJSON() {
    return datetime.strftime(this, '%Y-%m-%d');
}

Date.prototype.toJSON = toJSON;

Upvotes: 3

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