Question

138

Sort an array so that null values always come last

rated 0 times [ 144] [ 6] / answers: 1 / hits: 118775 / 9 Years ago, thu, april 23, 2015, 12:00:00

I need to sort an array of strings, but I need it so that null is always last. For example, the array:

var arr = [a, b, null, d, null]

When sorted ascending I need it to be sorted like [a, b, d, null, null] and when sorted descending I need it to be sorted like [d, b, a, null, null].

Is this possible? I tried the solution found below but it's not quite what I need.

How can one compare string and numeric values (respecting negative values, with null always last)?

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krystadesiraeo

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2 Years ago

answered 9 Years ago skyler · Accepted Answer

Check out .sort() and do it with custom sorting.
Example

function alphabetically(ascending) {

  return function (a, b) {

    // equal items sort equally

    if (a === b) {

        return 0;

    }



    // nulls sort after anything else

    if (a === null) {

        return 1;

    }

    if (b === null) {

        return -1;

    }



    // otherwise, if we're ascending, lowest sorts first

    if (ascending) {

        return a < b ? -1 : 1;

    }



    // if descending, highest sorts first

    return a < b ? 1 : -1;

  };

}







var arr = [null, a, z, null, b];



console.log(arr.sort(alphabetically(true)));

console.log(arr.sort(alphabetically(false)));