Sorting nested arrays of objects by date
arrays, date, javascript, object, sorting
Solution
According to Underscore.js documentation, you should simply write your own iterator for that cause. Something like this:
_.sortBy(dateGroups, function(arrayElement) {
//element will be each array, so we just return a date from first element in it
return arrayElement[0].date.getTime();
});
Problem
I'm trying to sort an array that looks like this: ``` var dateGroups = [ [ {age:20, date: Fri Feb 03 2012 14:30:00 GMT+1100 (EST)}, {age:12, date: Fri Feb 03 2012 18:20:00 GMT+1100 (EST)}, {age:18, date: Fri Feb 03 2012 21:43:00 GMT+1100 (EST)} ], [ {age:32, date: Fri Feb 01 2012 10:54:00 GMT+1100 (EST)}, {age:44, date: Fri Feb 01 2012 11:45:00 GMT+1100 (EST)}, ], [ {age:22, date: Fri Feb 05 2012 10:54:00 GMT+1100 (EST)}, {age:22, date: Fri Feb 05 2012 18:22:00 GMT+1100 (EST)}, ] ] ``` The objects inside dateGroups' nested arrays are already sorted in ascending order, but I also want to sort the arrays themselves based on the grouped dates. In this case the array should then look like this: ``` var dateGroups = [ [ {age:32, date: Fri Feb 01 2012 10:54:00 GMT+1100 (EST)}, {age:44, date: Fri Feb 01 2012 11:45:00 GMT+1100 (EST)}, ], [ {age:20, date: Fri Feb 03 2012 14:30:00 GMT+1100 (EST)}, {age:12, date: Fri Feb 03 2012 18:20:00 GMT+1100 (EST)}, {age:18, date: Fri Feb 03 2012 21:43:00 GMT+1100 (EST)} ], [ {age:22, date: Fri Feb 05 2012 10:54:00 GMT+1100 (EST)}, {age:22, date: Fri Feb 05 2012 18:22:00 GMT+1100 (EST)}, ] ] ``` The function used to sort should also return the new sorted version of dateGroups. I've tried using Underscore.js's `sortBy()` function but I can't figure out how to sort the arrays based on the value of a property inside one of the objects. Is there a specific way to sort Date objects? Or are they sorted in the same way as numbers or letters?