Updated fromScale util to return top or bottom of scale, updated specs to reflect new fromScale behavior.

lib/utils.js

@@ -255,7 +255,15 @@ var addCoreExtensions = function addCoreExtensions() {
   //
   // Returns an integer representing the scaled value
   Number.prototype.fromScale = function(start, end) {
-    return (this - Math.min(start, end)) / (Math.max(start, end) - Math.min(start, end));
+    var val = (this - Math.min(start, end)) / (Math.max(start, end) - Math.min(start, end));
+
+    if (val > 1) {
+      val =  1;
+    } else if (val < 0){
+      val = 0;
+    }
+
+    return val;
   };
 
   // Public: Convert value from (0..1) scale to new (start, end) scale

test/specs/utils.spec.js

@@ -25,6 +25,14 @@ describe("Utils", function() {
         it("converts floats", function() {
           expect(2.5.fromScale(0, 10)).to.be.eql(0.25);
         });
+
+        it("should return 1 if the number goes above the top of the scale", function() {
+          expect((15).fromScale(0, 10)).to.be.eql(1);
+        });
+
+        it("should return 0 if the number goes below the bottom of the scale", function() {
+          expect((5).fromScale(10, 20)).to.be.eql(0);
+        });
       });
 
       describe("#toScale", function() {
@@ -32,6 +40,14 @@ describe("Utils", function() {
           expect((0.5).toScale(0, 10)).to.be.eql(5);
         });
 
+        it("bottom of scale should be returned when value goes below it", function() {
+          expect((-5).toScale(0, 10)).to.be.eql(0);
+        });
+
+        it("top of scale should be returned when value goes above it", function() {
+          expect((15).toScale(0, 10)).to.be.eql(10);
+        });
+
         it("converts to floats", function() {
           expect(0.25.toScale(0, 10)).to.be.eql(2.5);
         });