Javascript Sorting Multidimensional array using index

Question

I am having issues on identifying the actually index of the array its being sorted.

My list is a bit messy:

    masterList =[];
    masterList.push([1,"NY","New York, NY 10036, United States",40.760262,-73.993286,"07/30/2015"]);
    masterList.push([2,"Chgo","Chicago, IL, United States",41.878113,-87.629799,"07/06/2015"]);
    masterList.push([3,"Japan","Japan",11.1111,-11.1111,"07/22/2015"]);
    masterList.push([4,"China","China",22.2222,-22.2222,"07/18/2015"]);

masterList.sort(sortdates());

function sortdates(a,b) {
        return function(a, b){
                a = Date(a[5]);
                console.log(a);
                b = Date(b[5]);
                return a - b;
            };
}

Obviously this isn't working. I want to be able to grab the 6st index on the multidimensional array and sort by that.

I tried looking everywhere.. but I don't have a "key" that ties to my array.. so I can't really use that to point it. Any suggestions?

Instead of masterList.sort(sortdates()) you have to write masterList.sort(sortdates). You have to provide a reference to a function, not call the sort-function. — hgoebl
– hgoebl, Commented Jul 30, 2015 at 15:30

Joseph Marikle · Accepted Answer · 2015-07-30 15:36:26Z

1

There are three problems. First, you should pass a function handle to the sort function. You are calling the function instead. Second, the function should not return a function and should accept two parameters. Third and most important, you need to create new instances of the date object. It's not a static method.

The returning a function could work, so the real problem you have is the lack of the new keyword

    masterList =[];
    masterList.push([1,"NY","New York, NY 10036, United States",40.760262,-73.993286,"07/30/2015"]);
    masterList.push([2,"Chgo","Chicago, IL, United States",41.878113,-87.629799,"07/06/2015"]);
    masterList.push([3,"Japan","Japan",11.1111,-11.1111,"07/22/2015"]);
    masterList.push([4,"China","China",22.2222,-22.2222,"07/18/2015"]);

masterList.sort(sortdates);

function sortdates(a,b) {
                a = new Date(a[5]);
                console.log(a);
                b = new Date(b[5]);
                return a - b;
}

answered Jul 30, 2015 at 15:36

Joseph Marikle

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4 Comments

SQLNub Over a year ago

thanks! hmm I put in console.log(masterList), but nothing is happening.. the array doesn't seemed to be sorted?

Joseph Marikle Over a year ago

@SQLNub It seems to sort. I'll put together a better demo.

SQLNub Over a year ago

it is sorted! ya i think i forgot the new part. Thank you!

Joseph Marikle Over a year ago

@SQLNub aw dang it... I just finished it too. :P jsfiddle.net/nrf5e8hc Oh well. Glad the issue is resolved.

Munick · Accepted Answer · 2015-07-30 15:48:50Z

1

Looks like you've got an extra function in there. This would work better, no need to return another function.

function sortdates(a,b) {
    a = new Date(a[5]);
    console.log(a);
    b = new Date(b[5]);
    return a - b;
}

Then you can pass sortdates (without the ()) to sort

edited Jul 30, 2015 at 15:48

answered Jul 30, 2015 at 15:32

Munick

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1 Comment

SQLNub Over a year ago

I just tried using your suggested code in combination of without (), then console.log(masterList); shortly after .sort... doesn't seem to be reflecting the new array?

Tom Teman · Accepted Answer · 2015-07-30 15:33:25Z

-1

How about using underscore.js?

Then you can use sortBy as follows:

var sorted = _.sortBy(masterList, function(value){ return new Date(value[5]).getTime(); });

Here is a fiddle with the solution

edited Jul 30, 2015 at 15:33

answered Jul 30, 2015 at 15:32

Tom Teman

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