Fix unexpected use of undefined with Boolean()

Airbnb style guide recommends checking booleans this way or using
(!!window.FormData). The latter is more confusing for many.

While !! is indeed 0.2% faster than Boolean(), it's called
micro-optimization. There is no noticeable difference to the user in our
use scenario and I prefer more readable code any day.

Fixes ESLint no-undefined warning using Airbnb ES5 config.

Reference: https://jsperf.com/boolean-conversion-speed

1 files changed, 1 insertions, 1 deletions

diff --git a/js/cabinet.js b/js/cabinet.js
index 2f3a3a6..a74bb40 100644
--- a/js/cabinet.js
+++ b/js/cabinet.js
@@ -23,7 +23,7 @@
 /* jshint browser:true, jquery:true */
 (function($) {
   $.hasFileAPI = function hasFileAPI() {
-    return (window.FormData !== undefined);
+    return Boolean(window.FormData);
   };
 
   $.fn.cabinet = function(input) {