Question

I have a JSON object which returns a list of events with dates and times, I want to add a counter to the next event time, but i am not sure how to approach this?

Basically, my JSON is like:

[{"name": "BAKER-CROSSROADS", "country": "USA", "lon": "165.25", "yield": "21", "lat": "11.58", "depth": ".027", "date": "1946/07/24 21:35:00", "id": "1"}, {"name": "VENUS", "country": "USA", "lon": "-116.2", "yield": "10", "lat": "37.19", "depth": ".03", "date": "1958/02/22 01:00:00", "id": "10", "fill": "green"}, {"name": "HATCHIE", "country": "USA", "lon": "-116.03", "yield": "20", "lat": "37.058", "depth": ".061", "date": "1963/02/08 16:00:01", "id": "100", "fill": "green"}, {"name": "CLIMAX:Upshot-Knothole", "country": "USA", "lon": "-116.0183", "yield": "61", "lat": "37.0875", "depth": "-.41", "date": "1953/06/04 11:14:57", "id": "1000", "fill": "red"}, {"name": "BRAVO:Castle", "country": "USA", "lon": "165.274", "yield": "15000", "lat": "11.698", "depth": "0", "date": "1954/02/28 18:45:00", "id": "1001", "fill": "red"}, ....

so for each object:

{“name”: “BAKER-CROSSROADS”, “country”: “USA”, “lon”: “165.25”, “yield”: “21”, “lat”: “11.58”, “depth”: “.027”, “date”: “1946/07/24 21:35:00”, “id”: “1”}

{“name”: “VENUS”, “country”: “USA”, “lon”: “-116.2”, “yield”: “10”, “lat”: “37.19”, “depth”: “.03”, “date”: “1958/02/22 01:00:00”, “id”: “10”, “fill”: “green”}

…

here is the code that reads the json file:

    this.loadNext = function () {
    d3.json("./data/detonations.json", function(datum) {
        for(var i = datum.length - 1; i >= 0; --i) {
            var o = datum[i];
            //console.log(o);
            message = {
                country: o.country
                ,date: o.date
                ,depth: o.depth
                ,lon: o.lon
                ,lat: o.lat
                ,type: o.type
                ,yield: o.yield
            };
            self.doSomething(message)
        }
    });
}

i would like to calculate the date/time difference, so in this case the difference of “1958/02/22 01:00:00” and “1946/07/24 21:35:00” and pass this to the message array?

Answer 1

To have this difference in millisecondes, you may use

var diff = (new Date(s2)).getTime() - (new Date(s1)).getTime();

That’s because the format you have is directly parsable by the Date class.