<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script src="jquery-2.0.3.js"></script>
<script>
$(function(){
for(var attr in $.support){
$('body').append( '<div>'+attr+':'+$.support[attr]+'</div>' );
}
/* 根据这些属性，判断浏览器类型
checkOn:true
optSelected:true
reliableMarginRight:true
boxSizingReliable:true
pixelPosition:false
noCloneChecked:true
optDisabled:true
radioValue:true
checkClone:true
focusinBubbles:false
clearCloneStyle:true
cors:true
ajax:true
*/
var oDiv = document.getElementById('div1');
oDiv.onfocusin = function(){//鼠标移入事件
alert(123);
};
var div = document.createElement('div');
div.style.backgroundColor = 'red';
div.cloneNode(true).style.backgroundColor = '';
alert( div.style.backgroundColor );
var div = $('<div>');
div.css('backgroundColor','red');
div.clone().css('backgroundColor','');
alert( div.css('backgroundColor') );
});
</script>
</head>
<body>
<div id="div1">
<input type="text">
</div>
</body>
</html>
//兼容性，support是做兼容性检测，检测完之后实施是通过钩子机制。
jQuery.support = (function( support ) {//右边函数会立即执行
var input = document.createElement("input"),
fragment = document.createDocumentFragment(),//文档碎片
div = document.createElement("div"),
select = document.createElement("select"),
opt = select.appendChild( document.createElement("option") );
// input.type默认是text,基本都有，
if ( !input.type ) {
return support;
}
//改成复选框
input.type = "checkbox";
//新版本value的值是'on',老版本value的值是'',所以新本版support.checkOn=true,老版本support.checkOn=false,就可以通过support.checkOn属性值进行浏览器类型判断。
support.checkOn = input.value !== "";
// 狐火chrome下拉子项默认是选中的，ie默认不选中。
support.optSelected = opt.selected;
// 定义初始值
support.reliableMarginRight = true;
support.boxSizingReliable = true;
support.pixelPosition = false;
// Make sure checked status is properly cloned
// Support: IE9, IE10
//先让input选中，然后克隆，再判断选中状态，火狐chromeIE10以上都是选中的，ie低版本不是选中。
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)
//下拉菜单禁止，子项有没有禁止。
select.disabled = true;
support.optDisabled = !opt.disabled;
// Check if an input maintains its value after becoming a radio
// Support: IE9, IE10
input = document.createElement("input");
input.value = "t";
input.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.appendChild( input );
// Support: Safari 5.1, Android 4.x, Android 2.3
// old WebKit doesn't clone checked state correctly in fragments
support.checkClone = fragment.cloneNode( true ).cloneNode( true ).lastChild.checked;
// Support: Firefox, Chrome, Safari
// Beware of CSP restrictions (https://developer.mozilla.org/en/Security/CSP)
support.focusinBubbles = "onfocusin" in window;
//首先定义一个div的背景剪切是内容剪切，然后复制一份设置背景剪切为空，然后看原来div的背景剪切还是不是内容剪切。
div.style.backgroundClip = "content-box";
div.cloneNode( true ).style.backgroundClip = "";
support.clearCloneStyle = div.style.backgroundClip === "content-box";
//下面的需要等dom加载完才能检测
jQuery(function() {
var container, marginDiv,
// Support: Firefox, Android 2.3 (Prefixed box-sizing versions).
//
divReset = "padding:0;margin:0;border:0;display:block;-webkit-box-sizing:content-box;-moz-box-sizing:content-box;box-sizing:content-box",
body = document.getElementsByTagName("body")[ 0 ];
if ( !body ) {
// Return for frameset docs that don't have a body
return;
}
//创建一个container来检测
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 = "";
// Support: Firefox, Android 2.3 (Prefixed box-sizing versions).
div.style.cssText = "-webkit-box-sizing:border-box;-moz-box-sizing:border-box;box-sizing:border-box;padding:1px;border:1px;display:block;width:4px;margin-top:1%;position:absolute;top:1%";
// Workaround failing boxSizing test due to offsetWidth returning wrong value
// with some non-1 values of body zoom, ticket #13543
jQuery.swap( body, body.style.zoom != null ? { zoom: 1 } : {}, function() {
support.boxSizing = div.offsetWidth === 4;
});
// 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";
// Support: Android 2.3
// Check if 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
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 );
});
return support;//返回json
})( {} );//实参json
