jquery/src/css/support.js

define( [
	"../core",
	"../var/document",
	"../var/documentElement",
	"../var/support"
], function( jQuery, document, documentElement, support ) {

( function() {
	var pixelPositionVal, pixelMarginRightVal, gBCRDimensionsVal, boxSizingReliableVal,
		reliableHiddenOffsetsVal, reliableMarginRightVal, reliableMarginLeftVal,
		container = document.createElement( "div" ),
		div = document.createElement( "div" );

	// Finish early in limited (non-browser) environments
	if ( !div.style ) {
		return;
	}

	div.style.cssText = "float:left;opacity:.5";

	// Support: IE<9
	// Make sure that element opacity exists (as opposed to filter)
	support.opacity = div.style.opacity === "0.5";

	// Verify style float existence
	// (IE uses styleFloat instead of cssFloat)
	support.cssFloat = !!div.style.cssFloat;

	div.style.backgroundClip = "content-box";
	div.cloneNode( true ).style.backgroundClip = "";
	support.clearCloneStyle = div.style.backgroundClip === "content-box";

	container = document.createElement( "div" );
	container.style.cssText = "border:0;width:8px;height:0;top:0;left:-9999px;" +
		"padding:0;margin-top:1px;position:absolute";
	div.innerHTML = "";
	container.appendChild( div );

	jQuery.extend( support, {
		reliableHiddenOffsets: function() {
			if ( pixelPositionVal == null ) {
				computeStyleTests();
			}
			return reliableHiddenOffsetsVal;
		},

		boxSizingReliable: function() {

			// We're checking for pixelPositionVal here instead of boxSizingReliableVal
			// since that compresses better and they're computed together anyway.
			if ( pixelPositionVal == null ) {
				computeStyleTests();
			}
			return boxSizingReliableVal;
		},

		gBCRDimensions: function() {
			if ( pixelPositionVal == null ) {
				computeStyleTests();
			}
			return gBCRDimensionsVal;
		},

		pixelMarginRight: function() {

			// Support: Android 4.0-4.3
			if ( pixelPositionVal == null ) {
				computeStyleTests();
			}
			return pixelMarginRightVal;
		},

		pixelPosition: function() {
			if ( pixelPositionVal == null ) {
				computeStyleTests();
			}
			return pixelPositionVal;
		},

		reliableMarginRight: function() {

			// Support: Android 2.3
			if ( pixelPositionVal == null ) {
				computeStyleTests();
			}
			return reliableMarginRightVal;
		},

		reliableMarginLeft: function() {

			// Support: IE <=8 only, Android 4.0 - 4.3 only, Firefox <=3 - 37
			if ( pixelPositionVal == null ) {
				computeStyleTests();
			}
			return reliableMarginLeftVal;
		}
	} );

	function computeStyleTests() {
		var contents, divStyle,
			documentElement = document.documentElement;

		// Setup
		documentElement.appendChild( container );

		div.style.cssText =

			// Support: Android 2.3
			// Vendor-prefix box-sizing
			"-webkit-box-sizing:border-box;box-sizing:border-box;" +
			"position:relative;display:block;" +
			"margin:auto;border:1px;padding:1px;" +
			"top:1%;width:50%";

		// Support: IE<9
		// Assume reasonable values in the absence of getComputedStyle
		pixelPositionVal = boxSizingReliableVal = reliableMarginLeftVal = false;
		pixelMarginRightVal = reliableMarginRightVal = true;

		// Support: IE<9
		// In IE8 gBCR doesn't report width & height.
		gBCRDimensionsVal = !!div.getBoundingClientRect().width;

		// Check for getComputedStyle so that this code is not run in IE<9.
		if ( window.getComputedStyle ) {
			divStyle = window.getComputedStyle( div );
			pixelPositionVal = ( divStyle || {} ).top !== "1%";
			reliableMarginLeftVal = ( divStyle || {} ).marginLeft === "2px";
			boxSizingReliableVal = ( divStyle || { width: "4px" } ).width === "4px";

			// Support: Android 4.0 - 4.3 only
			// Some styles come back with percentage values, even though they shouldn't
			div.style.marginRight = "50%";
			pixelMarginRightVal = ( divStyle || { marginRight: "4px" } ).marginRight === "4px";

			// Support: Android 2.3 only
			// Div with explicit width and no margin-right incorrectly
			// gets computed margin-right based on width of container (#3333)
			// WebKit Bug 13343 - getComputedStyle returns wrong value for margin-right
			contents = div.appendChild( document.createElement( "div" ) );

			// Reset CSS: box-sizing; display; margin; border; padding
			contents.style.cssText = div.style.cssText =

				// Support: Android 2.3
				// Vendor-prefix box-sizing
				"-webkit-box-sizing:content-box;box-sizing:content-box;" +
				"display:block;margin:0;border:0;padding:0";
			contents.style.marginRight = contents.style.width = "0";
			div.style.width = "1px";

			reliableMarginRightVal =
				!parseFloat( ( window.getComputedStyle( contents ) || {} ).marginRight );

			div.removeChild( contents );
		}

		// Support: IE<9
		// Check if table cells still have offsetWidth/Height when they are set
		// to display:none and there are still other visible table cells in a
		// table row; if so, offsetWidth/Height are not reliable for use when
		// determining if an element has been hidden directly using
		// display:none (it is still safe to use offsets if a parent element is
		// hidden; don safety goggles and see bug #4512 for more information).
		div.innerHTML = "<table><tr><td></td><td>t</td></tr></table>";
		contents = div.getElementsByTagName( "td" );
		contents[ 0 ].style.cssText = "margin:0;border:0;padding:0;display:none";
		reliableHiddenOffsetsVal = contents[ 0 ].offsetHeight === 0;
		if ( reliableHiddenOffsetsVal ) {
			contents[ 0 ].style.display = "";
			contents[ 1 ].style.display = "none";
			reliableHiddenOffsetsVal = contents[ 0 ].offsetHeight === 0;
		}

		// Teardown
		documentElement.removeChild( container );
	}

} )();

return support;

} );