add documentation to methods (#129)

js/common/model/Optic.js

@@ -462,6 +462,8 @@ class Optic {
   }
 
   /**
+   * get the bounds of the optically "active" component
+   * In practice, it means that we exclude the backing (fill) of the mirror
    * @public
    * @returns {Bounds2}
    */

js/common/model/Ray.js

@@ -29,10 +29,12 @@ class Ray extends Ray2 {
 
     assert && assert( typeof options.length === 'number' );
 
+    // @public {number}
     this.length = options.length;
   }
 
   /**
+   * Set the length of the ray
    * @public
    * @param {number} length
    */

js/common/model/Ruler.js

@@ -55,6 +55,7 @@ class Ruler {
   }
 
   /**
+   * is the ruler horizontal
    * @public
    * @returns {boolean}
    */
@@ -63,6 +64,7 @@ class Ruler {
   }
 
   /**
+   * is the ruler vertical
    * @public
    * @returns {boolean}
    */

js/common/model/SourceObject.js

@@ -84,10 +84,10 @@ class SourceObject {
 
       const scale = representation.isObject ? OBJECT_SCALE_FACTOR : SOURCE_SCALE_FACTOR;
 
-      // update the value of the offset
+      // {Vector2} update the value of the offset
       this.offsetPosition = representation.offsetPosition.dividedScalar( scale );
 
-      // update the left top position - the firstPosition is the ground truth when changing representation
+      // {Vector2} update the left top position - the firstPosition is the ground truth when changing representation
       this.leftTopProperty.value = this.firstPositionProperty.value.plus( this.offsetPosition );
     } );
 

js/common/view/GeometricOpticsRulerNode.js

@@ -162,6 +162,7 @@ class GeometricOpticsRulerNode extends RulerNode {
   }
 
   /**
+   * dispose of the listeners on this ruler
    * @public
    */
   dispose() {
@@ -170,6 +171,7 @@ class GeometricOpticsRulerNode extends RulerNode {
   }
 
   /**
+   * set the orientation of the ruler
    * @public
    */
   setOrientation() {
@@ -181,6 +183,7 @@ class GeometricOpticsRulerNode extends RulerNode {
   }
 
   /**
+   * sets the position of the ruler
    * @public
    */
   setPosition() {

js/common/view/GeometricOpticsRulersLayer.js

@@ -124,6 +124,7 @@ class GeometricOpticRulersLayer extends Node {
   }
 
   /**
+   * dispose function for the two ruler orientations
    * @public
    */
   disposeRulers() {

js/common/view/GeometricOpticsScreenView.js

@@ -309,6 +309,7 @@ class GeometricOpticsScreenView extends ScreenView {
   }
 
   /**
+   * time stepper
    * @public
    */
   step( dt ) {

js/common/view/SourceObjectNode.js

@@ -227,6 +227,7 @@ class SourceObjectNode extends Node {
   }
 
   /**
+   * reset this node
    * @public
    */
   reset() {