Compare arrays as (multi-) sets

Question

I\'m looking for an efficient way to find out whether two arrays contain same amounts of equal elements (in the == sense), in any order:

foo = {         


        

Answer 1

Like this perhaps?

var foo = {}; var bar=[];
var a = [3,2,1,foo]; var b = [foo,1,2,3];

function comp(a,b)
{
    // immediately discard if they are of different sizes
    if (a.length != b.length) return false;

    b = b.slice(0); // clone to keep original values after the function

    a.forEach(function(e) {
        var i;
        if ((i = b.indexOf(e)) != -1)
            b.splice(i, 1);
    });

    return !b.length;
}

comp(a,b);