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Harry
Harry

Reputation: 57

JavaScript loop through Json dates

I'm trying to use JavaScript to loop through a json file which has time periods (starting date/time and ending date/time), and check if now (current date time) falls between any time period in such list.

Following is my code, but can't get where I'm wrong. Any help?

<html>
<script type="text/javascript">
    var data = {
        "period": {
            "startend": [{
                "startDate": "2015-11-17 15:43:37",
                "endDate": "2015-11-18 19:43:37"
            }, {
                "startDate": "2015-12-17 19:43:37",
                "endDate": "2016-01-17 19:43:37"
            }, {
                "startDate": "2015-04-17 19:43:37",
                "endDate": "2015-04-18 19:43:37"
            }]
        }
    }

    var periodArray = data.period.startend;
    var curDate = new Date();
    var datetime = curDate.getFullYear() + '-' + curDate.getMonth() + '-' + curDate.getDate() + ' ' + curDate.getHours() + ':' + curDate.getMinutes() + ':' + curDate.getSeconds();

    for (i = 0; i < periodArray.length ; i++) {
        var obj = periodArray[i]
            if (datetime > obj.startDate && datetime < obj.endDate){
                alert('Falls within period');
            } else {
                alert('Not within any period');
            }
    }
</script>

Upvotes: 2

Views: 1296

Answers (2)

Hunan Rostomyan
Hunan Rostomyan

Reputation: 2176

The basic idea is to convert the date strings to actual Date objects so they can be compared with the current date (new Date()). Let's begin by defining a helper function that when initialized, closes over the current date, producing a function that takes a start date and an end date, either in String or in Date form, and returns true if and only if the closed over current date is in the range.

Definition.

// () -> (([String|Date] * [String|Date]) -> Boolean)
// When initialized, closes over the current date and returns
// a predicate on String or Date objects. 
function includesNow() {
  var curDate = new Date();
  return function(start, end) {
    var startDate = (typeof start === "string")
      ? new Date(start) : start;
    var endDate = (typeof end === "string")
      ? new Date(end) : end;
    return (curDate > startDate) && (curDate < endDate);
  };
}

Usage.

With the help of the helper function, we can then pretty easily filter the "current" dates:

// Get the list of (date string) objects.
var allDates = data.period.startend;

// Capture the current date, returning the date range comparator.
var comparator = includesNow();

// Get the list of those (date string) objects `obj`
// that satisfy `comparator(obj.startDate, obj.endDate) === true`.
var currentDates = allDates.filter(function(obj) {
  return comparator(obj.startDate, obj.endDate);
});

// This is a function of current date, so will be empty at some point.
currentDates[0];
// => Object {startDate: "2015-11-17 15:43:37", endDate: "2015-11-18 19:43:37"}

If you know your objects will always be Strings and never actual Date objects, then you can simplify includesNow considerably. If you're interested in the closed range be sure to replace > and < with ≥ and ≤, respectively.

Upvotes: 3

Exziled
Exziled

Reputation: 493

JSON date is not a date object. It's a string. You're trying to compare a Date obj to a String.

If the JSON date was an ISO formatted date you could do : 

var dateStr = JSON.parse(date);
var realDate = new Date(dateStr);

realDate would now have a js date object. Unfortunately in your example the startDate and endDate are not ISO strings.

This would be the easiest/cleanest solution. Otherwise you could always get the JSON date strings and break them apart with substring() and convert the years/months/days with Number(); and then compare them that way?

Upvotes: 0

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