Javascript排序数组-在compare函数中调用函数

Question

I have an array of objects that contain some address data including latitude and longitude.

I have a function that calculates the distance between two sets of lat/long coordinates.

I need to sort my array from closest to farthest from a specific set of lat/long.

I'm trying to use arr.sort(comparefunction) but no luck so far. Is it possible to use an external function inside my compare function to do it?

Here is the code I tried.

function getDistance (lat1, lon1, lat2, lon2, unit) {
    var radlat1 = Math.PI * lat1/180
    var radlat2 = Math.PI * lat2/180
    var theta = lon1-lon2
    var radtheta = Math.PI * theta/180
    var dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
    if (dist > 1) {
        dist = 1;
    }
    dist = Math.acos(dist)
    dist = dist * 180/Math.PI
    dist = dist * 60 * 1.1515
    if (unit=="K") { dist = dist * 1.609344 }
    if (unit=="N") { dist = dist * 0.8684 }
    return dist
}


let distributors = [
    {
        city: "A",
        lat: 44.3384925,
        long: -59.6993207,
        name: "Name 1",
    },
    {
        city: "B",
        lat: 44.3384925,
        long: -78.6993207,
        name: "Name 2",
    },
    {
        city: "C",
        lat: 64.3384925,
        long: -39.6993207,
        name: "Name 3",
    }
];

let sortedDist = distributors.sort(function(a, b){ 

    if(getDistance(44.3617171302915, -79.65860486970848, a.lat, a.long, "K") < getDistance(44.3617171302915, -79.65860486970848, a.lat, a.long, "K")){
        return -1;
    }
    if(getDistance(44.3617171302915, -79.65860486970848, a.lat, a.long, "K") > getDistance(44.3617171302915, -79.65860486970848, a.lat, a.long, "K")){
        return 1;
    }
    return 0;
})

So in this scenario, the second element in the array is the closest in distance from 44.3617171302915, -79.65860486970848 , but I console.log(sortedDist) and nothing has changed.

Answer 1

The problem is that you're comparing a against a , try:

let sortedDist = distributors.sort(function(a, b){ 

    if(getDistance(44.3617171302915, -79.65860486970848, a.lat, a.long, "K") < getDistance(44.3617171302915, -79.65860486970848, b.lat, b.long, "K")){
        return -1;
    }
    if(getDistance(44.3617171302915, -79.65860486970848, a.lat, a.long, "K") > getDistance(44.3617171302915, -79.65860486970848, b.lat, b.long, "K")){
        return 1;
    }
    return 0;
})

or the same with shorter syntax:

let sortedDist = distributors.sort(function(a, b){ 

    let aDist = getDistance(44.3617171302915, -79.65860486970848, a.lat, a.long, "K");
    let bDist = getDistance(44.3617171302915, -79.65860486970848, b.lat, b.long, "K");

    return aDist - bDist;
})