turf.square needs mercator coordinates to work correctly

[vin-ni]

I've been struggling with getting a correct turf.square using real world coordinates until I realized I needed to pass mercator coordinates to make it work correctly on earth.

Maybe we could just add a hint in the docs or add a function that detects wgs84 coordinates and makes the correct calculation / conversion.

This is the result doing it with Wgs84 lat long:

And the expected result with conversion to mercator and back:

Quick code for the second result:

	var originalbboxx = [-2.440916, 49.4627643, -2.4579404, 49.4828877]
	
	var point1 = [originalbboxx[0], originalbboxx[1]]
	var point2 = [originalbboxx[2], originalbboxx[3]]

	var converted1 = turf.toMercator(point1);
	var converted2 = turf.toMercator(point2);

	var squared = turf.square([converted1[0],converted1[1],converted2[0],converted2[1]] )

	var squarept1 = [squared[0], squared[1]]
	var squarept2 = [squared[2], squared[3]]

	var wsg1 = turf.toWgs84(squarept1);
	var wsg2 = turf.toWgs84(squarept2);

	var newSquaredBbox = [wsg1[0],wsg1[1],wsg2[0],wsg2[1] ]

[vin-ni]

Actually I needed to do the aspectratio comparison with lat long, but calculate the values with mercato. So I rewrote the square function like that:

unction square(bbox) {
    var west = bbox[0];
    var south = bbox[1];
    var east = bbox[2];
    var north = bbox[3];

    var horizontalDistance = turf.distance(bbox.slice(0, 2), [east, south]);
	var verticalDistance = turf.distance(bbox.slice(0, 2), [west, north]);
	
	var converted1 = turf.toMercator([bbox[0],bbox[1]]);
	var converted2 = turf.toMercator([bbox[2],bbox[3]]);

	var westM = converted1[0];
    var southM = converted1[1];
    var eastM = converted2[0];
	var northM = converted2[1];
	
	var mercatorResult = []

    if (horizontalDistance >= verticalDistance) {
        var verticalMidpoint = (southM + northM) / 2;
        mercatorResult = [
            westM,
            verticalMidpoint - ((eastM - westM) / 2),
            eastM,
            verticalMidpoint + ((eastM - westM) / 2)
        ];
    } else {
        var horizontalMidpoint = (westM + eastM) / 2;
        mercatorResult = [
            horizontalMidpoint - ((northM - southM) / 2),
            southM,
            horizontalMidpoint + ((northM - southM) / 2),
            northM
        ];
	}
	
	// convert back
	var wsg1 = turf.toWgs84([mercatorResult[0],mercatorResult[1]]);
	var wsg2 = turf.toWgs84([mercatorResult[2],mercatorResult[3]]);

	return [wsg1[0],wsg1[1],wsg2[0],wsg2[1]]
}