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Finding date closest to today from array of objects

I have parsed a CSV that slices like this:

data[0]
>>Date:08/23/2018, Organizer:RadioShack, Event:Promotion


I found a somewhat helpful question in: Find closest date in array with JavaScript, however I had trouble adapting it from an array of dates to dates stored within an array of objects. I have dates from data[0] to data[10]. It's not a terribly long dataset, however I would like to code it better than my current crude approach:

data[0]

data[10]

var dateArray = ;
dateArray[0] = data[0].Date;
dateArray[1] = data[1].Date;
…

console.log(dateArray.filter(function(d) return d - today > 0; ))


That gives me all dates after today's date, which is a start, but I'm still falling short on finding the date closest to today.

Question: I thought maybe I could just write a for loop to give me that array faster, but I still wonder: is there a way I can find the date closest to today's date from an array of objects and store that date in:

var closestEventDate = ???


1 Answer
1

You could reduce your dateArray to the date closest to today:

const today = new Date();
const closest = data.reduce((a, b) => a.Date - today < b.Date - today ? a : b);


Live Example:

var now = Date.now();
var ONE_DAY_IN_MS = 86400000;
function randomDate()
return new Date(now + (5 * ONE_DAY_IN_MS - Math.round(Math.random() * 10 * ONE_DAY_IN_MS)));

var data = [
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate()
];

console.log("Entries:");
data.forEach(function(entry)
console.log(entry.Date.toISOString());
);

const today = new Date();
const closest = data.reduce((a, b) => a.Date - today < b.Date - today ? a : b);

console.log("today", today.toISOString());
console.log("closest", closest.Date.toISOString());

.as-console-wrapper
max-height: 100% !important;


Or the closest after today:

const today = new Date();
const closest = data.reduce((a, b) =>
const adiff = a.Date - today;
return adiff > 0 && adiff < b.Date - today ? a : b;
);


Live Example:

var now = Date.now();
var ONE_DAY_IN_MS = 86400000;
function randomDate()
return new Date(now + (5 * ONE_DAY_IN_MS - Math.round(Math.random() * 10 * ONE_DAY_IN_MS)));

var data = [
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate(),
Date: randomDate()
];

console.log("Entries:");
data.forEach(function(entry)
console.log(entry.Date.toISOString());
);

const today = new Date();
const closest = data.reduce((a, b) =>
const adiff = a.Date - today;
return adiff > 0 && adiff < b.Date - today ? a : b;
);

console.log("today", today.toISOString());
console.log("closest", closest.Date.toISOString());

.as-console-wrapper
max-height: 100% !important;


reduce

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