--- /dev/null
+/*!
+ * is-number <https://github.com/jonschlinkert/is-number>
+ *
+ * Copyright (c) 2014-2017, Jon Schlinkert.
+ * Released under the MIT License.
+ */
+
+'use strict';
+
+module.exports = function isNumber(num) {
+ var type = typeof num;
+
+ if (type === 'string' || num instanceof String) {
+ // an empty string would be coerced to true with the below logic
+ if (!num.trim()) return false;
+ } else if (type !== 'number' && !(num instanceof Number)) {
+ return false;
+ }
+
+ return (num - num + 1) >= 0;
+};