Adding OL.String.isNumeric method to test for numeric strings. r=crschmidt (closes #1441)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@7451 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/BaseTypes.js

@@ -134,6 +134,31 @@ OpenLayers.String = {
             }
         }
         return tokens.join("");
+    },
+    
+    /**
+     * Property: OpenLayers.String.numberRegEx
+     * Used to test strings as numbers.
+     */
+    numberRegEx: /^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/,
+    
+    /**
+     * APIFunction: OpenLayers.String.isNumeric
+     * Determine whether a string contains only a numeric value.
+     *
+     * Examples:
+     * (code)
+     * OpenLayers.String.isNumeric("6.02e23") // true
+     * OpenLayers.String.isNumeric("12 dozen") // false
+     * OpenLayers.String.isNumeric("4") // true
+     * OpenLayers.String.isNumeric(" 4 ") // false
+     * (end)
+     *
+     * Returns:
+     * {Boolean} String contains only a number.
+     */
+    isNumeric: function(value) {
+        return OpenLayers.String.numberRegEx.test(value);
     }
 
 };