From df78a8345e33c3bbec0948a4cd3b1ec7977e920f Mon Sep 17 00:00:00 2001
From: jokebookservice1 <jokebookyeye@gmail.com>
Date: Wed, 10 Oct 2018 18:36:06 +0100
Subject: [PATCH] refactor: use utility for whitespace-testing

---
 src/blocks/scratch3_looks.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/blocks/scratch3_looks.js b/src/blocks/scratch3_looks.js
index 92f4995b5..dbf4be7a3 100644
--- a/src/blocks/scratch3_looks.js
+++ b/src/blocks/scratch3_looks.js
@@ -353,6 +353,7 @@ class Scratch3LooksBlocks {
      */
     _setCostume (target, requestedCostume, optZeroIndex) {
         if (typeof requestedCostume === 'number') {
+            // Numbers should be treated as comments, always
             target.setCostume(optZeroIndex ? requestedCostume : requestedCostume - 1);
         } else {
             const costumeIndex = target.getCostumeIndexByName(requestedCostume.toString());
@@ -363,8 +364,10 @@ class Scratch3LooksBlocks {
                 target.setCostume(target.currentCostume + 1);
             } else if (requestedCostume === 'previous costume') {
                 target.setCostume(target.currentCostume - 1);
-            } else if (!isNaN(requestedCostume) &&
-                        (typeof requestedCostume !== 'string' || /\d/g.test(requestedCostume))) {
+            // Try to cast the string to a number (and treat it as a costume index)
+            // Pure whitespace should not be treated as a number (JS casts this to 0)
+            // Note: isNaN will cast the string to a number before checking if it's NaN
+            } else if (!(isNaN(requestedCostume) || Cast.isWhiteSpace(requestedCostume))) {
                 target.setCostume(optZeroIndex ? Number(requestedCostume) : Number(requestedCostume) - 1);
             }
         }