Have numericLerp work in fixed point based on the longest operand.

Restrict the set of strings considered numbers to those JS reasonable can treat as numbers.

diff --git a/demo.html b/demo.html
index 81941dc1e790159a8c2e3b8b4c15f417fe01f166..de1902d8fb3a8eca937762782c1db4015decf690 100644 (file)
--- a/demo.html
+++ b/demo.html
@@ -17,7 +17,7 @@
           ["Do you like green eggs and ham?", "I do not like them, Sam-I-am."],
           ["apple core", "core dump"],
           ["rgb(255, 0, 0)", "rgb(0, 128, 255)"],
-          ["1.5 + 1.5 = 3.0", "3 + 7 = 10"],
+          ["1.50 + 1.50 = 3.0", "3 + 7 = 10"],
           ["ZALGO̸", "ZA̢LG͜O"],
           ["", "Typing, one letter at a time."],
           ["( ﾉﾟ▽ﾟ)ﾉ", "( ╯︵╰)"]

diff --git a/string-lerp.js b/string-lerp.js
index 607abc1a4592d6a7aa702818ee6afb0038d232a1..46a55bf152769f14c15af203a3cc972ce64791e8 100644 (file)
--- a/string-lerp.js
+++ b/string-lerp.js
@@ -154,7 +154,7 @@
         return patch(partial, target);
     }
 
-    var NUMBERS = /(-?\d+(?:\.\d+)?)/g;
+    var NUMBERS = /(-?\d{1,20}(?:\.\d{1,20})?)/g;
 
     function areNumericTwins(source, target) {
         /** Check if a and b differ only in numerals */
@@ -184,7 +184,6 @@
             numerals gives undefined results.
         */
 
-        // TODO: Try to preserve precision of the original numbers.
         var sourceParts = source.split(NUMBERS);
         var targetParts = target.split(NUMBERS);
         var destParts = targetParts;
@@ -194,9 +193,10 @@
             var part = nlerp(+sourcePart, +targetPart, amount);
             var sourcePoint = sourcePart.indexOf(".");
             var targetPoint = targetPart.indexOf(".");
-            if (sourcePoint === -1 && targetPoint === -1)
-                part = Math.round(part);
-            targetParts[i] = part.toString();
+            var point = Math.max(
+                sourcePoint >= 0 ? (sourcePart.length - 1) - sourcePoint : 0,
+                targetPoint >= 0 ? (targetPart.length - 1) - targetPoint : 0);
+            targetParts[i] = part.toFixed(point);
         }
         return targetParts.join("");
     }

diff --git a/tests/string-lerp.js b/tests/string-lerp.js
index 0a68921793c96ddfe07ea1093c78a9d4fe724e1e..2eccba65491a1a1878fcd66fe55f04452be413a5 100644 (file)
--- a/tests/string-lerp.js
+++ b/tests/string-lerp.js
@@ -157,6 +157,12 @@ JS.Test.describe('numeric lerp', function () { with (this) {
         assertEqual("12.3", lerp("0.0", "100.0", 0.123));
     }});
 
+    it("thinks about precision", function () { with (this) {
+        assertEqual("12.30", lerp("0", "100.00", 0.123));
+        assertEqual("12.30", lerp("0.00", "100", 0.123));
+        assertEqual("12.300", lerp("0.000", "100.000", 0.123));
+    }});
+
     it("computes parameters outside [0, 1]", function () { with (this) {
         assertEqual("Giving 110%", lerp("Giving 0%", "Giving 100%", 1.1));
     }});