# getGeoDiff

{% hint style="info" %} <mark style="color:$info;">**ACCURACY MODES**</mark>

* <mark style="color:$info;">**High‑accuracy mode**</mark> <mark style="color:$info;"></mark><mark style="color:$info;">is based on the</mark> [<mark style="color:$info;">Vincenty formulae</mark>](https://en.wikipedia.org/wiki/Vincenty's_formulae) <mark style="color:$info;">(ellipsoidal Earth model, higher precision).</mark>
* <mark style="color:$info;">**Normal-accuracy mode**</mark> <mark style="color:$info;"></mark><mark style="color:$info;">is based on the</mark> [<mark style="color:$info;">Haversine formulae</mark>](https://en.wikipedia.org/wiki/Haversine_formula) <mark style="color:$info;">(spherical Earth model, faster, slightly less precise)</mark>
  {% endhint %}

## IMPORT

```typescript
import { getGeoDiff } from "@donedeal0/superdiff";
```

***

## FORMAT

### Input

```typescript
previousCoordinates: [number, number] | null | undefined;
  coordinates: [number, number] | null | undefined;
  options?: {
    unit?: "centimeter" | "foot" | "inch" | "kilometer" | "meter" | "mile" | "mile-scandinavian" | "millimeter" | "yard"; // "kilometer" by default
    accuracy?: "normal" | "high"; // "normal" by default
    maxDecimals?: number; // 2 by default,
    locale?: Intl.Locale | string; // "en-US" by default
  }
```

* `previousCoordinates`: the original coordinates (`[Longitude, Latitude]`).
* `coordinates`: the new coordinates (`[Longitude, Latitude]`).
* `options`
  * `unit`: the unit used for the returned distance.
  * `accuracy`:
    * `normal` (default): fastest mode, with a small error margin, based on Haversine formula.
    * `high`: slower but highly precise distance. Based on Vincenty formula.
  * `maxDecimals`: maximal decimals for the distance. Defaults to 2.
  * `locale`: the locale of your distance. Enables a locale‑aware distance label.

### Output

```typescript
type GeoDiff = {
    type: "geo";
    status: "added" | "deleted" | "error" | "equal" | "updated";
    diff: {
        coordinates: [number, number] | null;
        previousCoordinates: [number, number] | null;
        distance: number;
        unit: "centimeter" | "foot" | "inch" | "kilometer" | "meter" | "mile" | "mile-scandinavian" | "millimeter" | "yard";
        label: string,
        direction: "east" | "north" | "south" | "west" | "north-east" | "north-west" | "south-east" | "south-west" | "stationary";
    };
}
};
```

***

## USAGE

### Input

```diff
getGeoDiff(
- [2.3522, 48.8566],
+ [-0.1278, 51.5074]
);
```

{% hint style="info" %}
Coordinates follow GeoJSON order: \[longitude, latitude].
{% endhint %}

### Output

```diff
{
      type: "geo",
+     status: "updated",
      diff: {
+          coordinates: [-0.1278, 51.5074],
           previousCoordinates: [2.3522, 48.8566],
+          direction: "north-west",
+          distance: 343.56,
+          label: "343.56 kilometers",
+          unit: "kilometer"
        }
}
```