A clean way to do it would be to convert each date to a Date() and take the max

ES6:

new Date(Math.max(...a.map(e => new Date(e.MeasureDate))));

JS:

new Date(Math.max.apply(null, a.map(function(e) {
  return new Date(e.MeasureDate);
})));

where a is the array of objects.

What this does is map each of the objects in the array to a date created with the value of MeasureDate. This mapped array is then applied to the Math.max function to get the latest date and the result is converted to a date.

By mapping the string dates to JS Date objects, you end up using a solution like Min/Max of dates in an array?

--

A less clean solution would be to simply map the objects to the value of MeasureDate and sort the array of strings. This only works because of the particular date format you are using.

a.map(function(e) { return e.MeasureDate; }).sort().reverse()[0]

If performance is a concern, you may want to reduce the array to get the maximum instead of using sort and reverse.

Code is tested with IE,FF,Chrome and works properly:

var dates=[];
dates.push(new Date("2011/06/25"))
dates.push(new Date("2011/06/26"))
dates.push(new Date("2011/06/27"))
dates.push(new Date("2011/06/28"))
var maxDate=new Date(Math.max.apply(null,dates));
var minDate=new Date(Math.min.apply(null,dates));

1) Use map to extract the dates:

var dates = data.map(function(x) { return new Date(x[4]); })

2) Use Math.max / Math.min to get the highest / lowest dates:

var latest = new Date(Math.max.apply(null,dates));
var earliest = new Date(Math.min.apply(null,dates));

Try wrapping document.getElementById('date1').value in new Date().getTime() .

Also input type="date" accepts value as yyyy-mm-dd ; try using .toJSON() , String.prototype.slice() to set date properly for #maxdate as yyyy-mm-dd from value returned as maxDate

function checkMaxDate() {
  var dateArray = [];
  var date1 = dateArray.push(new Date(document.getElementById('date1').value).getTime());
  var date2 = dateArray.push(new Date(document.getElementById('date2').value).getTime());
  var maxDate = Math.max.apply(Math, dateArray);
  document.getElementById('maxdate').value = new Date(maxDate).toJSON().slice(0, 10);
}

Date 1:
<input type="date" id="date1" />Date 2:
<input type="date" id="date2" />Max Date:
<input type="date" id="maxdate" />
<button type="button" onclick="checkMaxDate()">Check</button>

You could compare the ISO 8601 date like strings and take the greater value.

var dates = ["2018-12-29T15:23:20.486695Z", "2018-12-29T15:23:21.613216Z", "2018-12-29T15:23:22.695710Z", "2018-12-29T15:23:24.013567Z", "2018-12-29T15:23:25.097649Z", "2018-12-29T15:23:26.692125Z", "2018-12-29T15:23:27.918561Z", "2018-12-29T15:23:29.217879Z", "2018-12-29T15:23:30.468284Z", "2018-12-29T15:23:31.548761Z"],
    latest = dates.reduce((a, b) => a > b ? a : b);

console.log(latest);