Support %S as an equivalent to %s

README.md

@@ -33,7 +33,7 @@ The placeholders in the format string are marked by `%` and are followed by one
     * `f` — yields a float as is; see notes on precision above
     * `g` — yields a float as is; see notes on precision above
     * `o` — yields an integer as an octal number
-    * `s` — yields a string as is
+    * `s` or `S` — yields a string as is
     * `t` — yields `true` or `false`
     * `T` — yields the type of the argument<sup><a href="#fn-1" name="fn-ref-1">1</a></sup>
     * `v` — yields the primitive value of the specified argument

src/sprintf.js

@@ -14,7 +14,7 @@
         not_json: /[^j]/,
         text: /^[^\x25]+/,
         modulo: /^\x25{2}/,
-        placeholder: /^\x25(?:([1-9]\d*)\$|\(([^\)]+)\))?(\+)?(0|'[^$])?(-)?(\d+)?(?:\.(\d+))?([b-gijostTuvxX])/,
+        placeholder: /^\x25(?:([1-9]\d*)\$|\(([^\)]+)\))?(\+)?(0|'[^$])?(-)?(\d+)?(?:\.(\d+))?([b-gijosStTuvxX])/,
         key: /^([a-z_][a-z_\d]*)/i,
         key_access: /^\.([a-z_][a-z_\d]*)/i,
         index_access: /^\[(\d+)\]/,
@@ -93,6 +93,7 @@
                         arg = arg.toString(8)
                     break
                     case 's':
+                    case 'S':
                         arg = String(arg)
                         arg = (match[7] ? arg.substring(0, match[7]) : arg)
                     break