03-support.js | |
|---|---|
| jQuery Annotated Source. | |
Chapter 3: Support | jQuery.support = (function() {
var div = document.createElement( "div" ),
documentElement = document.documentElement,
all,
a,
select,
opt,
input,
marginDiv,
support,
fragment,
body,
testElementParent,
testElement,
testElementStyle,
tds,
events,
eventName,
i,
isSupported; |
| Preliminary tests | div.setAttribute("className", "t");
div.innerHTML = " <link/><table></table><a href='/a' style='top:1px;float:left;opacity:.55;'>a</a><input type='checkbox'/>";
all = div.getElementsByTagName( "*" );
a = div.getElementsByTagName( "a" )[ 0 ]; |
| Can't get basic test support | if ( !all || !all.length || !a ) {
return {};
} |
| First batch of supports tests | select = document.createElement( "select" );
opt = select.appendChild( document.createElement("option") );
input = div.getElementsByTagName( "input" )[ 0 ];
support = { |
| IE strips leading whitespace when .innerHTML is used | leadingWhitespace: ( div.firstChild.nodeType === 3 ), |
| Make sure that tbody elements aren't automatically inserted IE will insert them into empty tables | tbody: !div.getElementsByTagName( "tbody" ).length, |
| Make sure that link elements get serialized correctly by innerHTML This requires a wrapper element in IE | htmlSerialize: !!div.getElementsByTagName( "link" ).length, |
| Get the style information from getAttribute (IE uses .cssText instead) | style: /top/.test( a.getAttribute("style") ), |
| Make sure that URLs aren't manipulated (IE normalizes it by default) | hrefNormalized: ( a.getAttribute( "href" ) === "/a" ), |
| Make sure that element opacity exists (IE uses filter instead) Use a regex to work around a WebKit issue. See #5145 | opacity: /^0.55$/.test( a.style.opacity ), |
| Verify style float existence (IE uses styleFloat instead of cssFloat) | cssFloat: !!a.style.cssFloat, |
| Make sure that if no value is specified for a checkbox that it defaults to "on". (WebKit defaults to "" instead) | checkOn: ( input.value === "on" ), |
| Make sure that a selected-by-default option has a working selected property. (WebKit defaults to false instead of true, IE too, if it's in an optgroup) | optSelected: opt.selected, |
| Test setAttribute on camelCase class. If it works, we need attrFixes when doing get/setAttribute (ie6/7) | getSetAttribute: div.className !== "t", |
| Will be defined later | submitBubbles: true,
changeBubbles: true,
focusinBubbles: false,
deleteExpando: true,
noCloneEvent: true,
inlineBlockNeedsLayout: false,
shrinkWrapBlocks: false,
reliableMarginRight: true
}; |
| 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; |
| Test to see if it's possible to delete an expando from an element Fails in Internet Explorer | try {
delete div.test;
} catch( e ) {
support.deleteExpando = false;
}
if ( !div.addEventListener && div.attachEvent && div.fireEvent ) {
div.attachEvent( "onclick", function() { |
| Cloning a node shouldn't copy over any bound event handlers (IE does this) | support.noCloneEvent = false;
});
div.cloneNode( true ).fireEvent( "onclick" );
} |
| Check if a radio maintains it's value after being appended to the DOM | input = document.createElement("input");
input.value = "t";
input.setAttribute("type", "radio");
support.radioValue = input.value === "t";
input.setAttribute("checked", "checked");
div.appendChild( input );
fragment = document.createDocumentFragment();
fragment.appendChild( div.firstChild ); |
| WebKit doesn't clone checked state correctly in fragments | support.checkClone = fragment.cloneNode( true ).cloneNode( true ).lastChild.checked;
div.innerHTML = ""; |
| Figure out if the W3C box model works as expected | div.style.width = div.style.paddingLeft = "1px";
body = document.getElementsByTagName( "body" )[ 0 ]; |
| We use our own, invisible, body unless the body is already present in which case we use a div (#9239) | testElement = document.createElement( body ? "div" : "body" );
testElementStyle = {
visibility: "hidden",
width: 0,
height: 0,
border: 0,
margin: 0
};
if ( body ) {
jQuery.extend( testElementStyle, {
position: "absolute",
left: -1000,
top: -1000
});
}
for ( i in testElementStyle ) {
testElement.style[ i ] = testElementStyle[ i ];
}
testElement.appendChild( div );
testElementParent = body || documentElement;
testElementParent.insertBefore( testElement, testElementParent.firstChild ); |
| Check if a disconnected checkbox will retain its checked value of true after appended to the DOM (IE6/7) | support.appendChecked = input.checked;
support.boxModel = div.offsetWidth === 2;
if ( "zoom" in div.style ) { |
| Check if natively block-level elements act like inline-block elements when setting their display to 'inline' and giving them layout (IE < 8 does this) | div.style.display = "inline";
div.style.zoom = 1;
support.inlineBlockNeedsLayout = ( div.offsetWidth === 2 ); |
| Check if elements with layout shrink-wrap their children (IE 6 does this) | div.style.display = "";
div.innerHTML = "<div style='width:4px;'></div>";
support.shrinkWrapBlocks = ( div.offsetWidth !== 2 );
}
div.innerHTML = "<table><tr><td style='padding:0;border:0;display:none'></td><td>t</td></tr></table>";
tds = div.getElementsByTagName( "td" ); |
| 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). (only IE 8 fails this test) | isSupported = ( tds[ 0 ].offsetHeight === 0 );
tds[ 0 ].style.display = "";
tds[ 1 ].style.display = "none"; |
| Check if empty table cells still have offsetWidth/Height (IE < 8 fail this test) | support.reliableHiddenOffsets = isSupported && ( tds[ 0 ].offsetHeight === 0 );
div.innerHTML = ""; |
| Check if div with explicit width and no margin-right incorrectly gets computed margin-right based on width of container. For more info see bug #3333 Fails in WebKit before Feb 2011 nightlies WebKit Bug 13343 - getComputedStyle returns wrong value for margin-right | if ( document.defaultView && document.defaultView.getComputedStyle ) {
marginDiv = document.createElement( "div" );
marginDiv.style.width = "0";
marginDiv.style.marginRight = "0";
div.appendChild( marginDiv );
support.reliableMarginRight =
( parseInt( ( document.defaultView.getComputedStyle( marginDiv, null ) || { marginRight: 0 } ).marginRight, 10 ) || 0 ) === 0;
} |
| Remove the body element we added | testElement.innerHTML = "";
testElementParent.removeChild( testElement ); |
| Technique from Juriy Zaytsev http://thinkweb2.com/projects/prototype/detecting-event-support-without-browser-sniffing/ We only care about the case where non-standard event systems are used, namely in IE. Short-circuiting here helps us to avoid an eval call (in setAttribute) which can cause CSP to go haywire. See: https://developer.mozilla.org/en/Security/CSP | if ( div.attachEvent ) {
for( i in {
submit: 1,
change: 1,
focusin: 1
} ) {
eventName = "on" + i;
isSupported = ( eventName in div );
if ( !isSupported ) {
div.setAttribute( eventName, "return;" );
isSupported = ( typeof div[ eventName ] === "function" );
}
support[ i + "Bubbles" ] = isSupported;
}
} |
| Null connected elements to avoid leaks in IE | testElement = fragment = select = opt = body = marginDiv = div = input = null;
return support;
})(); |
| Keep track of boxModel | jQuery.boxModel = jQuery.support.boxModel;
|