How can I pass an argument to callback while calling it from sort method

Question

How can I pass an argument to callback method while calling it from arrayobj.sort(sortFunction) method.I want to pass "sortOrder" to "Compare" as well to sort it accending or desecding.

var sortOrder = "asc";
var a = new Array(4, 11, 2, 10, 3, 1);
b = a.sort(Compare);   // how to pass "sortOrder" here

// Sorts array elements in ascending order numerically.
function Compare(first, second, sortOrder) // here sortOrder require 
{
    if(sortOrder == "asc"){
        if (first == second)
            return 0;
        if (first < second)
            return -1;
        else
            return 1; 
        }
    else{
        if (first == second)
            return 0;
        if (first < second)
            return 1;
        else
            return -1; 
        }


    }
}

For inline anonymous functions always prefer arrows a.sort((p,c) => compare(p,c)) — Redu
– Redu, Commented Apr 14, 2016 at 12:09

Nina Scholz · Accepted Answer · 2016-04-14 12:27:37Z

1

This solution returns a function for the selected sort order. If no order is specified, then the function for asc is used.

function getComparer(sortOrder) {
    return sortOrder === 'desc' ?
        function (a, b) { return b - a; } :
        function (a, b) { return a - b; };
}

var a = new Array(4, 11, 2, 10, 3, 1);

a.sort(getComparer());
document.write('<pre> ' + JSON.stringify(a, 0, 4) + '</pre>');
a.sort(getComparer('desc'));
document.write('<pre> ' + JSON.stringify(a, 0, 4) + '</pre>');

edited Apr 14, 2016 at 12:27

answered Apr 14, 2016 at 12:12

Nina Scholz

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2 Comments

Ruben Serrate Over a year ago

Nice. But I'd suggest changing the name of your "compare" function to something like "generateCompare" or something like that :) , it confused me for a second.

Nina Scholz Over a year ago

@RubenSerrate, better now?

gurvinder372 · Accepted Answer · 2016-04-14 12:06:14Z

1

Try this way

Replace

b = a.sort(Compare);

with

b = a.sort(function(a,b){
  return Compare(a, b, sortOrder);
});

DEMO

var sortOrder = "asc";
var a = new Array(4, 11, 2, 10, 3, 1);
b = a.sort(function(a,b){
  return Compare(a, b, sortOrder);
});

document.body.innerHTML += JSON.stringify(b,0,4);

function Compare(first, second, sortOrder) // here sortOrder require
{
    if(sortOrder == "asc"){
        if (first == second)
            return 0;
        if (first < second)
            return -1;
        else
            return 1; 
        }
    else{
        if (first == second)
            return 0;
        if (first < second)
            return 1;
        else
            return -1; 
        }


    }

answered Apr 14, 2016 at 12:06

gurvinder372

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Comments

Ruben Serrate · Accepted Answer · 2016-04-14 12:13:59Z

0

If the only use for your code is the one you've posted here, you can just remove sortOrder from the list of parameters, so that the variable you define at the top is still visible inside the function.

If not, either of the two previous answers are the way to go.

answered Apr 14, 2016 at 12:13

Ruben Serrate

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