Improve type checking in ol.RotationConstraint

src/ol/rotationconstraint.js

@@ -28,14 +28,20 @@ ol.RotationConstraint.none = function(rotation, delta) {
  */
 ol.RotationConstraint.createSnapToN = function(n) {
   var theta = 2 * Math.PI / n;
-  return function(rotation, delta) {
+  return (
+      /**
+       * @param {number|undefined} rotation Rotation.
+       * @param {number} delta Delta.
+       * @return {number|undefined} Rotation.
+       */
+      function(rotation, delta) {
         if (goog.isDef(rotation)) {
           rotation = Math.floor((rotation + delta) / theta + 0.5) * theta;
           return rotation;
         } else {
           return undefined;
         }
-  };
+      });
 };
 
 
@@ -45,7 +51,13 @@ ol.RotationConstraint.createSnapToN = function(n) {
  */
 ol.RotationConstraint.createSnapToZero = function(opt_tolerance) {
   var tolerance = opt_tolerance || 0.1;
-  return function(rotation, delta) {
+  return (
+      /**
+       * @param {number|undefined} rotation Rotation.
+       * @param {number} delta Delta.
+       * @return {number|undefined} Rotation.
+       */
+      function(rotation, delta) {
         if (goog.isDef(rotation)) {
           if (Math.abs(rotation + delta) <= tolerance) {
             return 0;
@@ -55,5 +67,5 @@ ol.RotationConstraint.createSnapToZero = function(opt_tolerance) {
         } else {
           return undefined;
         }
-  };
+      });
 };