Function getWidthOrHeight

src/css.js:110–181

( elem, dimension, extra )

}

function getWidthOrHeight( elem, dimension, extra ) {

	// Start with computed style
	var styles = getStyles( elem ),

		// To avoid forcing a reflow, only fetch boxSizing if we need it (gh-4322).
		// Fake content-box until we know it's needed to know the true value.
		boxSizingNeeded = isIE || extra,
		isBorderBox = boxSizingNeeded &&
			jQuery.css( elem, "boxSizing", false, styles ) === "border-box",
		valueIsBorderBox = isBorderBox,

		val = curCSS( elem, dimension, styles ),
		offsetProp = "offset" + dimension[ 0 ].toUpperCase() + dimension.slice( 1 );

	// Return a confounding non-pixel value or feign ignorance, as appropriate.
	if ( rnumnonpx.test( val ) ) {
		if ( !extra ) {
			return val;
		}
		val = "auto";
	}


	if (
		(

			// Fall back to offsetWidth/offsetHeight when value is "auto"
			// This happens for inline elements with no explicit setting (gh-3571)
			val === "auto" ||

			// Support: IE 9 - 11+
			// Use offsetWidth/offsetHeight for when box sizing is unreliable.
			// In those cases, the computed value can be trusted to be border-box.
			( isIE && isBorderBox ) ||

			( !support.reliableColDimensions() && nodeName( elem, "col" ) ) ||

			( !support.reliableTrDimensions() && nodeName( elem, "tr" ) )
		) &&

		// Make sure the element is visible & connected
		elem.getClientRects().length ) {

		isBorderBox = jQuery.css( elem, "boxSizing", false, styles ) === "border-box";

		// Where available, offsetWidth/offsetHeight approximate border box dimensions.
		// Where not available (e.g., SVG), assume unreliable box-sizing and interpret the
		// retrieved value as a content box dimension.
		valueIsBorderBox = offsetProp in elem;
		if ( valueIsBorderBox ) {
			val = elem[ offsetProp ];
		}
	}

	// Normalize "" and auto
	val = parseFloat( val ) || 0;