Linter and minor efficiency update

Resolves #33

jquery.visible.js

@@ -10,19 +10,22 @@
  * the user visible viewport of a web browser.
  * only accounts for vertical position, not horizontal.
  */
+ var $w=$(window);
  $.fn.visible = function(partial,hidden,direction,container){
 
  if (this.length < 1)
  return;
-
+
+ // Set direction default to 'both'.
+ direction = direction || 'both';
+
  var $t = this.length > 1 ? this.eq(0) : this,
  isContained = typeof container !== 'undefined' && container !== null,
- $w = isContained ? $(container) : $(window),
- wPosition = isContained ? $w.position() : 0,
+ $c = isContained ? $(container) : $w,
+ wPosition = isContained ? $c.position() : 0,
  t = $t.get(0),
- vpWidth = $w.outerWidth(),
- vpHeight = $w.outerHeight(),
- direction = (direction) ? direction : 'both',
+ vpWidth = $c.outerWidth(),
+ vpHeight = $c.outerHeight(),
  clientSize = hidden === true ? t.offsetWidth * t.offsetHeight : true;
 
  if (typeof t.getBoundingClientRect === 'function'){
@@ -56,7 +59,7 @@
 
  var viewTop = isContained ? 0 : wPosition,
  viewBottom = viewTop + vpHeight,
- viewLeft = $w.scrollLeft(),
+ viewLeft = $c.scrollLeft(),
  viewRight = viewLeft + vpWidth,
  position = $t.position(),
  _top = position.top,