Javascript custom array sort by array

Question

I currently have this function which sort an array alphabetically.

function compare(a,b) {
    if (a.subtitle < b.subtitle)
        return -1;
    if (a.subtitle > b.subtitle)
        return 1;
        return 0;
}

I need a similar function that sorts the array by another array. I tried writing it myself but i couldn't get my head around it so i ended up with nothing.

Example:

I need array1 to be sorted depending on where that item is in array2.

Array1 = ['quick','fox','the','brown'];
Array2 = ['the','quick','brown','fox'];

There is probably an easy answer that i am not seeing.

Edit:

Also any items that are in array1 that aren't in array 2 can just be tacked onto the end in no particular order or alphabetically whatever is easier.

Note that return 0; is the default here, and the indentation is deceptive. For this reason, use curly-braces with if-statements in javascript. — dwerner
– dwerner, Commented Aug 19, 2013 at 5:20

manuskc · Accepted Answer · 2013-08-19 07:40:53Z

2

Try this:

function compare(a,b, compareArray) {
    if ((compareArray.indexOf(a) != -1 && compareArray.indexOf(a) < compareArray.indexOf(b))
         ||  compareArray.indexOf(b) == -1)
        return -1;
    if ((compareArray.indexOf(a) > compareArray.indexOf(b))
         || compareArray.indexOf(a) == -1)
        return 1;
        return 0;
}

edited Aug 19, 2013 at 7:40

answered Aug 19, 2013 at 5:16

manuskc

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4 Comments

Mattigins Over a year ago

Which array is compareArray?

manuskc Over a year ago

compareArray would be Array2 in your question.

plalx Over a year ago

That's good, however you should create an index map for quick lookups.

Mattigins Over a year ago

Does this handle items that aren't in array2?

user2587132 · Accepted Answer · 2013-08-19 05:38:17Z

0

http://jsfiddle.net/AMSDE/

var Array1 = ['quick', 'fox', 'the', 'brown', 'abc']; //the array to be sorted
var Array2 = ['the', 'quick', 'brown', 'fox'];
var sortedAry = [];

for (var i = 0; i < Array2.length; i++) {
var index = Array1.indexOf(Array2[i]);
if (index !== -1) {
    console.log(index);
    sortedAry.push(Array2[i]);
    Array1.splice(index, 1);
}
}

for (var j = 0; j < Array1.length; j++) {
sortedAry.push(Array1[j]);
}

console.log(sortedAry);

answered Aug 19, 2013 at 5:38

user2587132

Comments

ruok · Accepted Answer · 2014-10-02 17:22:05Z

I ran across the need to do the same thing today, this was my solution:

var arr = [".", 5359, 1, 2, 3, 4, 6, 9, 15];
var priorities = [3, '.', 1, 4, 15, 9, 2, 6];

var resultArr = arr.filter( function(arrElement) { return priorities.indexOf(arrElement) >= 0 })
    .sort( function (a,b) { return priorities.indexOf(a) - priorities.indexOf(b) })
    .concat( arr.filter( function(arrElement) { return priorities.indexOf(arrElement) < 0})
);

console.log(resultArr.join(""));

console: 3.14159265359

jsfiddle based on @rps's answer

Basically, it picks out the elements that we have a preferred order for, sorts those, then appends the elements that we had no order preference for. As a bonus (at least for my use case), the sorting is non-destructive to the order of arr.

I'm not sure if this is better or worse, but I know I loathe for loops. :)

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