2.0: Reduce offset module. Close gh-1139.

src/offset.js

@@ -8,8 +8,8 @@ jQuery.fn.offset = function( options ) {
 	}
 
 	var docElem, win,
-		box = { top: 0, left: 0 },
 		elem = this[ 0 ],
+		box = { top: 0, left: 0 },
 		doc = elem && elem.ownerDocument;
 
 	if ( !doc ) {
@@ -30,33 +30,35 @@ jQuery.fn.offset = function( options ) {
 	}
 	win = getWindow( doc );
 	return {
-		top: box.top  + ( win.pageYOffset || docElem.scrollTop )  - ( docElem.clientTop  || 0 ),
-		left: box.left + ( win.pageXOffset || docElem.scrollLeft ) - ( docElem.clientLeft || 0 )
+		top: box.top + win.pageYOffset - docElem.clientTop,
+		left: box.left + win.pageXOffset - docElem.clientLeft
 	};
 };
 
 jQuery.offset = {
 
 	setOffset: function( elem, options, i ) {
-		var position = jQuery.css( elem, "position" );
+		var curPosition, curLeft, curCSSTop, curTop, curOffset, curCSSLeft, calculatePosition,
+			position = jQuery.css( elem, "position" ),
+			curElem = jQuery( elem ),
+			props = {};
 
-		// set position first, in-case top/left are set even on static elem
+		// Set position first, in-case top/left are set even on static elem
 		if ( position === "static" ) {
 			elem.style.position = "relative";
 		}
 
-		var curElem = jQuery( elem ),
-			curOffset = curElem.offset(),
-			curCSSTop = jQuery.css( elem, "top" ),
-			curCSSLeft = jQuery.css( elem, "left" ),
-			calculatePosition = ( position === "absolute" || position === "fixed" ) && jQuery.inArray("auto", [curCSSTop, curCSSLeft]) > -1,
-			props = {}, curPosition = {}, curTop, curLeft;
+		curOffset = curElem.offset();
+		curCSSTop = jQuery.css( elem, "top" );
+		curCSSLeft = jQuery.css( elem, "left" );
+		calculatePosition = ( position === "absolute" || position === "fixed" ) && ( curCSSTop + curCSSLeft ).indexOf("auto") > -1;
 
-		// need to be able to calculate position if either top or left is auto and position is either absolute or fixed
+		// Need to be able to calculate position if either top or left is auto and position is either absolute or fixed
 		if ( calculatePosition ) {
 			curPosition = curElem.position();
 			curTop = curPosition.top;
 			curLeft = curPosition.left;
+
 		} else {
 			curTop = parseFloat( curCSSTop ) || 0;
 			curLeft = parseFloat( curCSSLeft ) || 0;
@@ -75,6 +77,7 @@ jQuery.offset = {
 
 		if ( "using" in options ) {
 			options.using.call( elem, props );
+
 		} else {
 			curElem.css( props );
 		}
@@ -90,13 +93,14 @@ jQuery.fn.extend({
 		}
 
 		var offsetParent, offset,
-			parentOffset = { top: 0, left: 0 },
-			elem = this[ 0 ];
+			elem = this[ 0 ],
+			parentOffset = { top: 0, left: 0 };
 
-		// fixed elements are offset from window (parentOffset = {top:0, left: 0}, because it is it's only offset parent
+		// Fixed elements are offset from window (parentOffset = {top:0, left: 0}, because it is it's only offset parent
 		if ( jQuery.css( elem, "position" ) === "fixed" ) {
-			// we assume that getBoundingClientRect is available when computed position is fixed
+			// We assume that getBoundingClientRect is available when computed position is fixed
 			offset = elem.getBoundingClientRect();
+
 		} else {
 			// Get *real* offsetParent
 			offsetParent = this.offsetParent();
@@ -108,25 +112,25 @@ jQuery.fn.extend({
 			}
 
 			// Add offsetParent borders
-			parentOffset.top  += jQuery.css( offsetParent[ 0 ], "borderTopWidth", true );
+			parentOffset.top += jQuery.css( offsetParent[ 0 ], "borderTopWidth", true );
 			parentOffset.left += jQuery.css( offsetParent[ 0 ], "borderLeftWidth", true );
 		}
 
 		// Subtract parent offsets and element margins
-		// note: when an element has margin: auto the offsetLeft and marginLeft
-		// are the same in Safari causing offset.left to incorrectly be 0
 		return {
-			top:  offset.top  - parentOffset.top - jQuery.css( elem, "marginTop", true ),
-			left: offset.left - parentOffset.left - jQuery.css( elem, "marginLeft", true)
+			top: offset.top - parentOffset.top - jQuery.css( elem, "marginTop", true ),
+			left: offset.left - parentOffset.left - jQuery.css( elem, "marginLeft", true )
 		};
 	},
 
 	offsetParent: function() {
 		return this.map(function() {
 			var offsetParent = this.offsetParent || document.documentElement;
+
 			while ( offsetParent && ( !jQuery.nodeName( offsetParent, "html" ) && jQuery.css( offsetParent, "position") === "static" ) ) {
 				offsetParent = offsetParent.offsetParent;
 			}
+
 			return offsetParent || document.documentElement;
 		});
 	}
@@ -135,22 +139,20 @@ jQuery.fn.extend({
 
 // Create scrollLeft and scrollTop methods
 jQuery.each( {scrollLeft: "pageXOffset", scrollTop: "pageYOffset"}, function( method, prop ) {
-	var top = /Y/.test( prop );
+	var top = "pageYOffset" === prop;
 
 	jQuery.fn[ method ] = function( val ) {
 		return jQuery.access( this, function( elem, method, val ) {
 			var win = getWindow( elem );
 
 			if ( val === undefined ) {
-				return win ? (prop in win) ? win[ prop ] :
-					win.document.documentElement[ method ] :
-					elem[ method ];
+				return win ? win[ prop ] : elem[ method ];
 			}
 
 			if ( win ) {
 				win.scrollTo(
-					!top ? val : jQuery( win ).scrollLeft(),
-					top ? val : jQuery( win ).scrollTop()
+					!top ? val : window.pageXOffset,
+					top ? val : window.pageYOffset
 				);
 
 			} else {
@@ -161,9 +163,5 @@ jQuery.each( {scrollLeft: "pageXOffset", scrollTop: "pageYOffset"}, function( me
 });
 
 function getWindow( elem ) {
-	return jQuery.isWindow( elem ) ?
-		elem :
-		elem.nodeType === 9 ?
-			elem.defaultView || elem.parentWindow :
-			false;
+	return jQuery.isWindow( elem ) ? elem : elem.nodeType === 9 && elem.defaultView;
 }