转换数据的JavaScript

Question

In a for loop, I want to get different dates for every item. I had implemented the following and it was working fine:

//This retrieves the right dates:
result.date = offer.get("createdAt");
result.updated = exchange.get("updatedAt");
result.expiration = exchange.get("expirationDate");

I was getting:

2017-09-01T20:33:35.245Z
2017-08-01T19:07:15.510Z
2017-07-28T19:43:11.590Z

As I want to convert to date format and get only month, date, year and time, I implement this:

//This brings the same date every time;
var date = Date(offer.get("createdAt"));
result.date = date.substr(4, 17);
result.shortDate = result.date.substr(4, 11);

var expiration = Date(exchange.get("expirationDate"));
result.expiration = expiration.substr(4, 11);

var updated = Date(exchange.get("updatedAt"));
result.updated = updated.substr(4, 11);

But it keeps bringing the same date for every element:

Sep 02 2017 18:08
Sep 02 2017 18:08 (this should be a different date)
Sep 02 2017 18:08 (this should be a different date)

I don't what I am missing! Thanks a lot.

Answer 1

Okay, use the following code instead:

var date = new Date(offer.get("createdAt"));
result.date = date.toString().substr(4, 17);
result.shortDate = result.date.substr(4, 11);

var expiration = new Date(exchange.get("expirationDate"));
result.expiration = expiration.toString().substr(4, 11);

var updated = new Date(exchange.get("updatedAt"));
result.updated = updated.toString().substr(4, 11);

So, the issue is you are not using Date() with the new keyword.

Answer 2

Use the new keyword before Date() , without it, you're just creating today's date, then convert them to strings in order to use substr with them :

 var result = {}; var date = new Date("2017-09-01T20:33:35.245Z").toString(); result.date = date.substr(4, 17); result.shortDate = result.date.substr(4, 11); var expiration = new Date("2017-08-01T19:07:15.510Z").toString(); result.expiration = expiration.substr(4, 11); var updated = new Date("2017-07-28T19:43:11.590Z").toString(); result.updated = updated.substr(4, 11); console.log(result);