Added support for speed unit

README.md

@@ -17,7 +17,8 @@ var velocityLayer = L.velocityLayer({
 	displayOptions: {
 		velocityType: 'Global Wind',
 		displayPosition: 'bottomleft',
-		displayEmptyString: 'No velocity data'
+		displayEmptyString: 'No velocity data',
+		speedUnit: 'kt'
 	},
 	data: data,             // see demo/*.json, or wind-js-server for example data service
 
@@ -29,6 +30,9 @@ var velocityLayer = L.velocityLayer({
 });
 ```
 
+The speed unit option refers to the unit used to express the wind speed in the control.
+It can be `m/s` for meter per second, `k/h` for kilometer per hour or `kt` for knots. If not given defaults to `m/s`.
+
 ## Reference
 `leaflet-velocity` is possible because of things like:
 - [L.CanvasOverlay.js](https://gist.github.com/Sumbera/11114288)

dist/leaflet-velocity.js

@@ -152,11 +152,21 @@ L.CanvasLayer = (L.Layer ? L.Layer : L.Class).extend({
 L.canvasLayer = function () {
 	return new L.CanvasLayer();
 };
+function meterSec2Knots(meters) {
+	return meters / 0.514;
+}
+
+function meterSec2kilometerHour(meters) {
+	return meters * 3.6;
+}
+
 L.Control.Velocity = L.Control.extend({
 
 	options: {
 		position: 'bottomleft',
-		emptyString: 'Unavailable'
+		emptyString: 'Unavailable',
+		// Could be 'm/s' for meter per second, 'k/h' for kilometer per hour or 'kt' for knots
+		speedUnit: 'm/s'
 	},
 
 	onAdd: function onAdd(map) {
@@ -171,17 +181,24 @@ L.Control.Velocity = L.Control.extend({
 		map.off('mousemove', this._onMouseMove, this);
 	},
 
-	vectorToSpeed: function vectorToSpeed(uMs, vMs) {
+	vectorToSpeed: function vectorToSpeed(uMs, vMs, unit) {
 		var velocityAbs = Math.sqrt(Math.pow(uMs, 2) + Math.pow(vMs, 2));
-		return velocityAbs;
+		// Default is m/s
+		if (unit === 'k/h') {
+			return meterSec2kilometerHour(velocityAbs);
+		} else if (unit === 'kt') {
+			return meterSec2Knots(velocityAbs);
+		} else {
+			return velocityAbs;
+		}
 	},
 
 	vectorToDegrees: function vectorToDegrees(uMs, vMs) {
 		var velocityAbs = Math.sqrt(Math.pow(uMs, 2) + Math.pow(vMs, 2));
 		var velocityDirTrigTo = Math.atan2(uMs / velocityAbs, vMs / velocityAbs);
 		var velocityDirTrigToDegrees = velocityDirTrigTo * 180 / Math.PI;
 		var velocityDirTrigFromDegrees = velocityDirTrigToDegrees + 180;
-		return velocityDirTrigFromDegrees.toFixed(3);
+		return velocityDirTrigFromDegrees.toFixed(2);
 	},
 
 	_onMouseMove: function _onMouseMove(e) {
@@ -197,7 +214,7 @@ L.Control.Velocity = L.Control.extend({
 			var vMs = gridValue[1];
 			vMs = vMs > 0 ? vMs = vMs - vMs * 2 : Math.abs(vMs);
 
-			htmlOut = "<strong>" + this.options.velocityType + " Direction: </strong>" + self.vectorToDegrees(gridValue[0], vMs) + "°" + ", <strong>" + this.options.velocityType + " Speed: </strong>" + self.vectorToSpeed(gridValue[0], vMs).toFixed(1) + "m/s";
+			htmlOut = "<strong>" + this.options.velocityType + " Direction: </strong>" + self.vectorToDegrees(gridValue[0], vMs) + "°" + ", <strong>" + this.options.velocityType + " Speed: </strong>" + self.vectorToSpeed(gridValue[0], vMs, this.options.speedUnit).toFixed(2) + this.options.speedUnit;
 		} else {
 			htmlOut = this.options.displayEmptyString;
 		}