how to compare dates in javascript

Question

I'm trying to select dates bigger than in javascript function. My function return empty array and I don't know wher I'm doing mistake

var arr = ["2018-01-24T17:43:03.000Z","2018-01-25T17:43:03.000Z","2018-01-
26T17:43:03.000Z","2018-01-27T17:43:03.000Z"]
var biggerThanElements = arr.filter(x=>{
  x = new Date(x);
  element = new Date("2018-01-23T00:00:00.000Z");
  x > element
});

console.log(biggerThanElements)

You need an explicit `return` when using `{}` in an anonymous function don't you? — Carcigenicate, Jan 31 '18 at 14:11
If you're not averse to external libraries I highly recommend [moment.js](https://momentjs.com/) when working with dates and times. — Paul, Jan 31 '18 at 14:11
no you don't need a library.. youre doing it exactly right you just forgot to return.. — I wrestled a bear once., Jan 31 '18 at 14:12
Instead of using plain javascript for date manipulations using moment js. Please refer below url for you refrence https://jsfiddle.net/onigetoc/rzyz4wgp/ — Ashokreddy, Jan 31 '18 at 14:18

score 1 · Answer 1 · answered Jan 31 '18 at 14:12

You missed your return statement for change to return x > element

var arr = ["2018-01-24T17:43:03.000Z","2018-01-25T17:43:03.000Z","2018-01-26T17:43:03.000Z","2018-01-27T17:43:03.000Z"]
var biggerThanElements = arr.filter(x=>{
  x = new Date(x);
  element = new Date("2018-01-23T00:00:00.000Z");
   return x > element
});
console.log(biggerThanElements)

score 1 · Accepted Answer · answered Jan 31 '18 at 14:14

1

You could just compare directly with ISO 8601 dates/time strings.

var arr = ["2018-01-24T17:43:03.000Z", "2018-01-25T17:43:03.000Z", "2018-01-26T17:43:03.000Z", "2018-01-27T17:43:03.000Z"],
    biggerThanElements = arr.filter(x => x > "2018-01-23T00:00:00.000Z");

console.log(biggerThanElements);

answered Jan 31 '18 at 14:14

Nina Scholz

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this might not work if the date come from different sources as there are a few variables.. for example, the standard allows the ommision of the "T" or a "+00" instead of the "Z" – I wrestled a bear once. Jan 31 '18 at 14:19
1

the data should follow the same standard for comparison ... – Nina Scholz Jan 31 '18 at 14:22

Racil Hilan · Answer 3 · 2018-01-31T14:23:01.400

There are a few issues in your code:

You need to return the result return x > element.
You use the date 2018-01-23 and all your dates are "bigger".
It is highly recommended to declare all your variables (i.e. element).

Try this:

var arr = ["2018-01-24T17:43:03.000Z", "2018-01-25T17:43:03.000Z", "2018-01-26T17:43:03.000Z", "2018-01-27T17:43:03.000Z"]
var biggerThanElements = arr.filter(x => {
  x = new Date(x);
  var element = new Date("2018-01-25T00:00:00.000Z");
  return x > element
});
console.log(biggerThanElements);

how to compare dates in javascript

3 Answers3