diff --git a/utilities/filter.js b/utilities/filter.js
index 6bf7d28..c0055f5 100644
--- a/utilities/filter.js
+++ b/utilities/filter.js
@@ -4,16 +4,22 @@ function isBarcode(toFilter) {
 }
 let n = true;
 function isShelving(toFilter) {
+    if (!Array.isArray(toFilter)) {
+        let s = toFilter;
+        toFilter = Array;
+        toFilter[0] = s;
+    }
     const exp = /^[A-Z][A-Z][A-Z]$/;
-    toFilter.forEach(element => {
-        let state = exp.test(element);
+    for (let i = 0; i < toFilter.length; i++) {
+        let state = exp.test(toFilter[i]);
         if (state == false)
             n = false;
-    });
+    }
     if (n == false)
         return false;
     else
         return true;
 }
+
 exports.isBarcode = isBarcode;
 exports.isShelving = isShelving;