jQuery.clean使用方法及思路分析_jquery

创建一个div元素并插入到文档碎片中
处理xhtml风格标签
将elem包裹起来，并将包裹后的字符串作为div的innerHTML
如果包裹深度大于1，只留下第一层包裹元素
清除在ie6,7中空table标签自动加入的tbody
将在ie9以下浏览器中剔除的开头空白字符串作为div元素的第一个文本子节点
将elem重新赋值为div的子节点集合(nodeList对象),
移除本次循环中文档碎片中的div，保持下一次循环中干净的div元素　　　　

var nodeNames = "abbr|article|aside|audio|bdi|canvas|data|datalist|details|figcaption|figure|footer|" +
"header|hgroup|mark|meter|nav|output|progress|section|summary|time|video",
wrapMap = {
option: [ 1, "", "" ],
legend: [ 1, "

", "

" ],
thead: [ 1, "", "" ],
tr: [ 2, "", "" ],
td: [ 3, "", "" ],
col: [ 2, "", "" ],
area: [ 1, "" ],
_default: [ 0, "", "" ]
},
rxhtmlTag = /<(?!area|br|col|embed|hr|img|input|link|meta|param)(([\w:]+)[^>]*)\/>/gi,
rtagName = /<([\w:]+)/,
rtbody = /<tbody/i,
rhtml = /<|&#?\w+;/,
rleadingWhitespace = /^\s+/,
rcheckableType = /^(?:checkbox|radio)$/,
rscriptType = /\/(java|ecma)script/i;
// 设置复选框checkbox或单选框radio表单元素的默认选中状态
function fixDefaultChecked( elem ) {
if ( rcheckableType.test( elem.type ) ) {
elem.defaultChecked = elem.checked;
}
}
// 创建一个安全的文档碎片
function createSafeFragment( document ) {
var list = nodeNames.split( "|" ),
safeFrag = document.createDocumentFragment(); // ie6,7,8浏览器把safeFrage作为HTMLDocument类型
// 针对ie9以下浏览器
if ( safeFrag.createElement ) {
while ( list.length ) {
safeFrag.createElement(
list.pop()
);
}
}
return safeFrag;
}
// 模拟ES5中Array的新功能
// 该函数API：http://www.css88.com/jqapi-1.8/#p=jQuery.grep
jQuery.extend({
grep: function( elems, callback, inv ) {
var retVal,
ret = [],
i = 0,
length = elems.length;
inv = !!inv;
// Go through the array, only saving the items
// that pass the validator function
for ( ; i < length; i++ ) {
retVal = !!callback( elems[ i ], i );
if ( inv !== retVal ) {
ret.push( elems[ i ] );
}
}
return ret;
}
});

jQuery.extend({
clean: function( elems, context, fragment, scripts ) {
// 声明变量
var i, j, elem, tag, wrap, depth, div, hasBody, tbody, len, handleScript, jsTags,
safe = context === document && safeFragment,
ret = [];
// 确保变量context为文档根节点document
if ( !context || typeof context.createDocumentFragment === "undefined" ) {
context = document;
}
// Use the already-created safe fragment if context permits
for ( i = 0; (elem = elems[i]) != null; i++ ) {
// 如果elem为数字,则将其转换为字符串
if ( typeof elem === "number" ) {
elem += "";
}
// 如果elem为undefined,跳出本次循环
if ( !elem ) {
continue;
}
// Convert html string into DOM nodes
// 转换数组项(字符串)为DOM节点
if ( typeof elem === "string" ) {
// 如果不存在html实体编号或标签,则创建文本节点
if ( !rhtml.test( elem ) ) {
elem = context.createTextNode( elem );
}
// 处理是html标签字符串的数组项
else {
// Ensure a safe container in which to render the html
// safe为#document-fragment类型,在ie9以下浏览器中,safe为HTMLDocument类型节点,且nodeNames数组为空
safe = safe || createSafeFragment( context );
// 创建一个div元素并将其插入到文档碎片中
div = context.createElement("div");
safe.appendChild( div );
// Fix "XHTML"-style tags in all browsers
// 除了area,br,col,embed,hr,img,input,link,meta,param这些标签外,
// 将开始标签末尾加入斜杠的标签转换为开始和结束标签
elem = elem.replace(rxhtmlTag, "<$1></$2>");
// Go to html and back, then peel off extra wrappers
// 获取左边第一个标签元素
tag = ( rtagName.exec( elem ) || ["", ""] )[1].toLowerCase();
// 获取最外层元素的包裹元素,并将元素包裹在其中
wrap = wrapMap[ tag ] || wrapMap._default;
depth = wrap[0];
div.innerHTML = wrap[1] + elem + wrap[2];
// Move to the right depth
// 如果元素的包裹深度大于1,div重新赋值为元素最近的包裹元素(即:包含第一层包裹元素)
while ( depth-- ) {
div = div.lastChild;
}
// Remove IE's autoinserted from table fragments
// 在IE6,7中,清除字符串中空table标签中自动加入的tbody标签(手动加入的除外)
if ( !jQuery.support.tbody ) {
// String was a , *may* have spurious(伪造的)
// 判断字符串中是否拥有空tbody标签
hasBody = rtbody.test(elem);
// 如果最外层标签为table且table中没有手动加入tbody
// 变量tbody为div.firstChild.childNodes(自动加入的tbody标签集合)
tbody = tag === "table" && !hasBody ?
div.firstChild && div.firstChild.childNodes :
// String was a bare or
// 如果字符串中仅有一个空thead或tfoot标签
// 变量tbody为div.childNodes(字符串中的thead和tfoot标签集合)
wrap[1] === "" && !hasBody ?
div.childNodes :
[];
for ( j = tbody.length - 1; j >= 0 ; --j ) {
// 排除thead或tfoot标签
if ( jQuery.nodeName( tbody[ j ], "tbody" ) && !tbody[ j ].childNodes.length ) {
// 清除空table标签中自动加入的tbody
tbody[ j ].parentNode.removeChild( tbody[ j ] );
}
}
}
// IE completely kills leading whitespace when innerHTML is used
// 在ie9以下浏览器中,字符串以空白字符串开头,将空白字符串作为div元素的第一个文本子节点
if ( !jQuery.support.leadingWhitespace && rleadingWhitespace.test( elem ) ) {
div.insertBefore( context.createTextNode( rleadingWhitespace.exec(elem)[0] ), div.firstChild );
}
// 获取已经处理完毕的div子节点集合(nodeList对象)
elem = div.childNodes;
// Take out of fragment container (we need a fresh div each time)
// 在下一次循环处理字符串数组项前,清除处理创建过的div元素
div.parentNode.removeChild( div );
}
}
// 如果elem为DOM节点(文本节点)
if ( elem.nodeType ) {
ret.push( elem );
}
// 将nodeList对象中节点合并到返回的数组中
else {
jQuery.merge( ret, elem );
}
}
// Fix #11356: Clear elements from safeFragment
if ( div ) {
elem = div = safe = null;
}
// Reset defaultChecked for any radios and checkboxes
// about to be appended to the DOM in IE 6/7 (#8060)
// 在ie6,7中,拥有checked属性的单选按钮,复选框在插入到其他标签后,选中状态会失效(下面代码修复该bug)
if ( !jQuery.support.appendChecked ) {
for ( i = 0; (elem = ret[i]) != null; i++ ) {
if ( jQuery.nodeName( elem, "input" ) ) {
fixDefaultChecked( elem );
} else if ( typeof elem.getElementsByTagName !== "undefined" ) {
jQuery.grep( elem.getElementsByTagName("input"), fixDefaultChecked );
}
}
}
// Append elements to a provided document fragment
// 将ret数组中的各DOM节点插入到提供的文档碎片中
// 提取dom节点中的script节点，并添加到ret数组中，位置为其原父元素索引位置后
if ( fragment ) {
// Special handling of each script element
handleScript = function( elem ) {
// Check if we consider it executable
// 如果elem元素不存在type属性或者type值为javascript或者为ecmascript
if ( !elem.type || rscriptType.test( elem.type ) ) {
// Detach the script and store it in the scripts array (if provided) or the fragment
// Return truthy to indicate that it has been handled
return scripts ?
scripts.push( elem.parentNode ? elem.parentNode.removeChild( elem ) : elem ) :
fragment.appendChild( elem );
}
};
for ( i = 0; (elem = ret[i]) != null; i++ ) {
// Check if we're done after handling an executable script
if ( !( jQuery.nodeName( elem, "script" ) && handleScript( elem ) ) ) {
// Append to fragment and handle embedded scripts
// 将elem元素添加到文档碎片中并处理嵌入的脚本(script标签元素)
fragment.appendChild( elem );
if ( typeof elem.getElementsByTagName !== "undefined" ) {
// handleScript alters the DOM, so use jQuery.merge to ensure snapshot iteration
jsTags = jQuery.grep( jQuery.merge( [], elem.getElementsByTagName("script") ), handleScript );
// Splice the scripts into ret after their former ancestor and advance our index beyond them
// 将script标签添加到数组，位置为其原父元素索引位置后
ret.splice.apply( ret, [i + 1, 0].concat( jsTags ) );
i += jsTags.length;
}
}
}
}
return ret;
}
});