for (var i = 0; i < 10; i++) {
    var ndwi_test = ee.Number(ee.Dictionary(s2_ndwi_mean.get(i)).get('NDWI')).float()
    ndwi_array.push(ndwi_test)
}

ndwi_array= ee.Array(ndwi_array).sort()

cars = [
    {
        name: "Honda",
        speed: 80
    },

    {
        name: "BMW",
        speed: 180
    },
]


cars.sort(function(a, b) {
    return a.speed - b.speed;
})

var a = [[12, 'AAA'], [58, 'BBB'], [28, 'CCC'],[18, 'DDD']];

a.sort(sortFunction);

function sortFunction(a, b) {
    if (a[0] === b[0]) {
        return 0;
    }
    else {
        return (a[0] < b[0]) ? -1 : 1;
    }
}