How to sort an array of arrays by a specified element? [duplicate]

Question

I have an array of arrays, each array within the array is set up like this

[1, firstname, lastname, 22]

I have a total of 12 of these, I am trying to sort the arrays by the 4th element of each array in descending order but nothing I have tried has worked, namely I have been trying to do array.sort with a comparison function and having look at the 4th element in each array but cant get it to work. Here is what I currently have:

function sortArray (a, b){
    return a-b;
}

for (var k = 0; k<employeeArray.length; k++){
    var j = k-1;
    employeeArray.sort(sortArray([k][3],[j][3]));
}

What I was expecting was for the function to sort the arrays by the 4th element but it keeps throwing up Uncaught Type errors.

You're passing a numeric value to sort. You need to pass a function which returns such a numeric value. Something like employeeArray.sort((a, b) => b[3] - a[3]) — Scott Sauyet
– Scott Sauyet, Commented Nov 30, 2018 at 17:21

Joe Iddon · Accepted Answer · 2018-11-30 17:22:32Z

2

I would recommend reading up on how sort works.

The .sort method handles the sorting. You do not need a for-loop.

Instead, you need to make your function sort two entries properly:

function sortTwoArrays(a, b){
    return a[3] - b[3];
}

Now you can just pass this as the parameter to the .sort method of your employeeArray:

employeeArray.sort(sortTwoArrays);

which will modify the array.

answered Nov 30, 2018 at 17:22

Joe Iddon

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2 Comments

Ryan Over a year ago

Thank you! This is exactly what I was trying to do!

Joe Iddon Over a year ago

@Ryan Please accept then!

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