jquery/src/support.js

jQuery.support = (function() {

	var support, all, a, select, opt, input, fragment,
		div = document.createElement("div");

	// Setup
	div.setAttribute( "className", "t" );
	div.innerHTML = "  <link/><table></table><a>a</a><input type='checkbox'/>";

	// Support tests won't run in some limited or non-browser environments
	all = div.getElementsByTagName("*");
	a = div.getElementsByTagName("a")[ 0 ];
	if ( !all || !a || !all.length ) {
		return {};
	}

	// First batch of tests
	select = document.createElement("select");
	opt = select.appendChild( document.createElement("option") );
	input = div.getElementsByTagName("input")[ 0 ];

	a.style.cssText = "float:left;opacity:.5";
	support = {
		// Verify style float existence
		// (IE uses styleFloat instead of cssFloat)
		cssFloat: !!a.style.cssFloat,

		// Check the default checkbox/radio value ("" on WebKit; "on" elsewhere)
		checkOn: !!input.value,

		// Must access the parent to make an option select properly
		// Support: IE9, IE10
		optSelected: opt.selected,

		// jQuery.support.boxModel DEPRECATED in 1.8 since we don't support Quirks Mode
		boxModel: document.compatMode === "CSS1Compat",

		// Will be defined later
		noCloneEvent: true,
		reliableMarginRight: true,
		boxSizingReliable: true,
		pixelPosition: false
	};

	// Make sure checked status is properly cloned
	input.checked = true;
	support.noCloneChecked = input.cloneNode( true ).checked;

	// Make sure that the options inside disabled selects aren't marked as disabled
	// (WebKit marks them as disabled)
	select.disabled = true;
	support.optDisabled = !opt.disabled;

	// Check if an input maintains its value after becoming a radio
	input = document.createElement("input");
	input.value = "t";
	input.setAttribute( "type", "radio" );
	support.radioValue = input.value === "t";

	// #11217 - WebKit loses check when the name is after the checked attribute
	input.setAttribute( "checked", "t" );
	input.setAttribute( "name", "t" );

	fragment = document.createDocumentFragment();
	fragment.appendChild( input );

	// Check if a disconnected checkbox will retain its checked
	// value of true after appended to the DOM (IE6/7)
	support.appendChecked = input.checked;

	// WebKit doesn't clone checked state correctly in fragments
	support.checkClone = fragment.cloneNode( true ).cloneNode( true ).lastChild.checked;

	// Support: IE<9
	// Opera does not clone events (and typeof div.attachEvent === undefined).
	// IE9-10 clones events bound via attachEvent, but they don't trigger with .click()
	if ( div.attachEvent ) {
		div.attachEvent( "onclick", function() {
			support.noCloneEvent = false;
		});

		div.cloneNode( true ).click();
	}

	// Support: Firefox 17+
	// Beware of CSP restrictions (https://developer.mozilla.org/en/Security/CSP), test/csp.php
	div.setAttribute( "onfocusin", "t" );
	support.focusinBubbles = "onfocusin" in window || div.attributes.onfocusin.expando === false;

	// Run tests that need a body at doc ready
	jQuery(function() {
		var container, marginDiv, tds,
			divReset = "padding:0;margin:0;border:0;display:block;box-sizing:content-box;-moz-box-sizing:content-box;-webkit-box-sizing:content-box;",
			body = document.getElementsByTagName("body")[0];

		if ( !body ) {
			// Return for frameset docs that don't have a body
			return;
		}

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

		// Check box-sizing and margin behavior
		body.appendChild( container ).appendChild( div );
		div.innerHTML = "";
		div.style.cssText = "box-sizing:border-box;-moz-box-sizing:border-box;-webkit-box-sizing:border-box;padding:1px;border:1px;display:block;width:4px;margin-top:1%;position:absolute;top:1%;";
		support.boxSizing = ( div.offsetWidth === 4 );
		support.doesNotIncludeMarginInBodyOffset = ( body.offsetTop !== 1 );

		// Use window.getComputedStyle because jsdom on node.js will break without it.
		if ( window.getComputedStyle ) {
			support.pixelPosition = ( window.getComputedStyle( div, null ) || {} ).top !== "1%";
			support.boxSizingReliable = ( window.getComputedStyle( div, null ) || { width: "4px" } ).width === "4px";

			// Check if div with explicit width and no margin-right incorrectly
			// gets computed margin-right based on width of container. (#3333)
			// Fails in WebKit before Feb 2011 nightlies
			// WebKit Bug 13343 - getComputedStyle returns wrong value for margin-right
			marginDiv = div.appendChild( document.createElement("div") );
			marginDiv.style.cssText = div.style.cssText = divReset;
			marginDiv.style.marginRight = marginDiv.style.width = "0";
			div.style.width = "1px";

			support.reliableMarginRight =
				!parseFloat( ( window.getComputedStyle( marginDiv, null ) || {} ).marginRight );
		}

		body.removeChild( container );

		// Null elements to avoid leaks in IE
		container = div = tds = marginDiv = null;
	});

	// Null elements to avoid leaks in IE
	all = select = fragment = opt = a = input = null;

	return support;
})();