抓住自己最有兴趣的东西，由浅入深，循序渐进地学……
自HTML5标准的提出就得到非常多的关注，而作为全球使用用户最多的IE浏览器能够支持HTML5标准也是大家备受关注一个问题，让IE(包括IE6)支持HTML5元素，我们需要在HTML头部添加以下JavaScript，这是一个简单的document.createElement声明，利用条件注释针对IE来调用这个js文件。Opera，FireFox等其他非IE浏览器就会忽视这段代码，也不会存在http请求。
<!–[if IE]> <script src=”http://html5shiv.googlecode.com/svn/trunk/html5.js”></script> <![endif]–>
上面这段代码仅会在IE浏览器下运行，还有一点需要注意，在页面中调用html5.js文件必须添加在页面的head元素内，因为IE浏览器必须在元素解析前知道这个元素，所以这个js文件不能在页面底部调用。
这个html5的js文件是作者把他放在Google code project上提供给大家可以直接调用的，当然，如果觉得这样会影响你的网页打开速度，你可以把html5的js文件直接下载下来让后上传到自己的服务器单独调用。
以下是html5的js文件中的代码:
/*
HTML5 Shiv v3.7.0 | @afarkas @jdalton @jon_neal @rem | MIT/GPL2 Licensed
*/
(function(l,f){function m(){var a=e.elements;return"string"==typeof a?a.split(" "):a}function i(a){var b=n[a[o]];b||(b={},h++,a[o]=h,n[h]=b);return b}function p(a,b,c){b||(b=f);if(g)return b.createElement(a);c||(c=i(b));b=c.cache[a]?c.cache[a].cloneNode():r.test(a)?(c.cache[a]=c.createElem(a)).cloneNode():c.createElem(a);return b.canHaveChildren&&!s.test(a)?c.frag.appendChild(b):b}function t(a,b){if(!b.cache)b.cache={},b.createElem=a.createElement,b.createFrag=a.createDocumentFragment,b.frag=b.createFrag();
a.createElement=function(c){return!e.shivMethods?b.createElem(c):p(c,a,b)};a.createDocumentFragment=Function("h,f","return function(){var n=f.cloneNode(),c=n.createElement;h.shivMethods&&("+m().join().replace(/[\w\-]+/g,function(a){b.createElem(a);b.frag.createElement(a);return'c("'+a+'")'})+");return n}")(e,b.frag)}function q(a){a||(a=f);var b=i(a);if(e.shivCSS&&!j&&!b.hasCSS){var c,d=a;c=d.createElement("p");d=d.getElementsByTagName("head")[0]||d.documentElement;c.innerHTML="x<style>article,aside,dialog,figcaption,figure,footer,header,hgroup,main,nav,section{display:block}mark{background:#FF0;color:#000}template{display:none}</style>";
c=d.insertBefore(c.lastChild,d.firstChild);b.hasCSS=!!c}g||t(a,b);return a}var k=l.html5||{},s=/^<|^(?:button|map|select|textarea|object|iframe|option|optgroup)$/i,r=/^(?:a|b|code|div|fieldset|h1|h2|h3|h4|h5|h6|i|label|li|ol|p|q|span|strong|style|table|tbody|td|th|tr|ul)$/i,j,o="_html5shiv",h=0,n={},g;(function(){try{var a=f.createElement("a");a.innerHTML="<xyz></xyz>";j="hidden"in a;var b;if(!(b=1==a.childNodes.length)){f.createElement("a");var c=f.createDocumentFragment();b="undefined"==typeof c.cloneNode||
"undefined"==typeof c.createDocumentFragment||"undefined"==typeof c.createElement}g=b}catch(d){g=j=!0}})();var e={elements:k.elements||"abbr article aside audio bdi canvas data datalist details dialog figcaption figure footer header hgroup main mark meter nav output progress section summary template time video",version:"3.7.0",shivCSS:!1!==k.shivCSS,supportsUnknownElements:g,shivMethods:!1!==k.shivMethods,type:"default",shivDocument:q,createElement:p,createDocumentFragment:function(a,b){a||(a=f);
if(g)return a.createDocumentFragment();for(var b=b||i(a),c=b.frag.cloneNode(),d=0,e=m(),h=e.length;d<h;d++)c.createElement(e[d]);return c}};l.html5=e;q(f)})(this,document);
除了在网页中调用包含以上代码的js文件来让IE浏览器支持HTML5元素以外，你也可以以下面这种方式把代码直接添加到网页中。
<!–[if IE]>
<script>
(function(l,f){function m(){var a=e.elements;return"string"==typeof a?a.split(" "):a}function i(a){var b=n[a[o]];b||(b={},h++,a[o]=h,n[h]=b);return b}function p(a,b,c){b||(b=f);if(g)return b.createElement(a);c||(c=i(b));b=c.cache[a]?c.cache[a].cloneNode():r.test(a)?(c.cache[a]=c.createElem(a)).cloneNode():c.createElem(a);return b.canHaveChildren&&!s.test(a)?c.frag.appendChild(b):b}function t(a,b){if(!b.cache)b.cache={},b.createElem=a.createElement,b.createFrag=a.createDocumentFragment,b.frag=b.createFrag();
a.createElement=function(c){return!e.shivMethods?b.createElem(c):p(c,a,b)};a.createDocumentFragment=Function("h,f","return function(){var n=f.cloneNode(),c=n.createElement;h.shivMethods&&("+m().join().replace(/[\w\-]+/g,function(a){b.createElem(a);b.frag.createElement(a);return'c("'+a+'")'})+");return n}")(e,b.frag)}function q(a){a||(a=f);var b=i(a);if(e.shivCSS&&!j&&!b.hasCSS){var c,d=a;c=d.createElement("p");d=d.getElementsByTagName("head")[0]||d.documentElement;c.innerHTML="x<style>article,aside,dialog,figcaption,figure,footer,header,hgroup,main,nav,section{display:block}mark{background:#FF0;color:#000}template{display:none}</style>";
c=d.insertBefore(c.lastChild,d.firstChild);b.hasCSS=!!c}g||t(a,b);return a}var k=l.html5||{},s=/^<|^(?:button|map|select|textarea|object|iframe|option|optgroup)$/i,r=/^(?:a|b|code|div|fieldset|h1|h2|h3|h4|h5|h6|i|label|li|ol|p|q|span|strong|style|table|tbody|td|th|tr|ul)$/i,j,o="_html5shiv",h=0,n={},g;(function(){try{var a=f.createElement("a");a.innerHTML="<xyz></xyz>";j="hidden"in a;var b;if(!(b=1==a.childNodes.length)){f.createElement("a");var c=f.createDocumentFragment();b="undefined"==typeof c.cloneNode||
"undefined"==typeof c.createDocumentFragment||"undefined"==typeof c.createElement}g=b}catch(d){g=j=!0}})();var e={elements:k.elements||"abbr article aside audio bdi canvas data datalist details dialog figcaption figure footer header hgroup main mark meter nav output progress section summary template time video",version:"3.7.0",shivCSS:!1!==k.shivCSS,supportsUnknownElements:g,shivMethods:!1!==k.shivMethods,type:"default",shivDocument:q,createElement:p,createDocumentFragment:function(a,b){a||(a=f);
if(g)return a.createDocumentFragment();for(var b=b||i(a),c=b.frag.cloneNode(),d=0,e=m(),h=e.length;d<h;d++)c.createElement(e[d]);return c}};l.html5=e;q(f)})(this,document);
</script>
<![endif]–>
补充阅读：以下代码是发布在github.com上的html5shiv.js，版本：3.7.0，注释也比较完整。可能GitHub打开速度有些慢，这里就直接将代码复制贴过来，如果需要最新版本，地址：https://github.com/aFarkas/html5shiv/blob/master/src/html5shiv.js
/**
* @preserve HTML5 Shiv prev3.7.1 | @afarkas @jdalton @jon_neal @rem | MIT/GPL2 Licensed
*/
;(function(window, document) {
/*jshint evil:true */
/**version */
var version = '3.7.0';
/**Preset options */
var options = window.html5 || {};
/**Used to skip problem elements */
var reSkip = /^<|^(?:button|map|select|textarea|object|iframe|option|optgroup)$/i;
/**Not all elements can be cloned in IE **/
var saveClones = /^(?:a|b|code|div|fieldset|h1|h2|h3|h4|h5|h6|i|label|li|ol|p|q|span|strong|style|table|tbody|td|th|tr|ul)$/i;
/**Detect whether the browser supports default html5 styles */
var supportsHtml5Styles;
/**Name of the expando, to work with multiple documents or to re-shiv one document */
var expando = '_html5shiv';
/**The id for the the documents expando */
var expanID = 0;
/**Cached data for each document */
var expandoData = {};
/**Detect whether the browser supports unknown elements */
var supportsUnknownElements;
(function() {
try {
var a = document.createElement('a');
a.innerHTML = '<xyz></xyz>';
//if the hidden property is implemented we can assume, that the browser supports basic HTML5 Styles
supportsHtml5Styles = ('hidden' in a);
supportsUnknownElements = a.childNodes.length == 1 || (function() {
// assign a false positive if unable to shiv
(document.createElement)('a');
var frag = document.createDocumentFragment();
return (
typeof frag.cloneNode == 'undefined' ||
typeof frag.createDocumentFragment == 'undefined' ||
typeof frag.createElement == 'undefined'
);
}());
} catch(e) {
// assign a false positive if detection fails => unable to shiv
supportsHtml5Styles = true;
supportsUnknownElements = true;
}
}());
/*--------------------------------------------------------------------------*/
/**
* Creates a style sheet with the given CSS text and adds it to the document.
* @private
* @param {Document} ownerDocument The document.
* @param {String} cssText The CSS text.
* @returns {StyleSheet} The style element.
*/
function addStyleSheet(ownerDocument, cssText) {
var p = ownerDocument.createElement('p'),
parent = ownerDocument.getElementsByTagName('head')[0] || ownerDocument.documentElement;
p.innerHTML = 'x<style>' + cssText + '</style>';
return parent.insertBefore(p.lastChild, parent.firstChild);
}
/**
* Returns the value of `html5.elements` as an array.
* @private
* @returns {Array} An array of shived element node names.
*/
function getElements() {
var elements = html5.elements;
return typeof elements == 'string' ? elements.split(' ') : elements;
}
/**
* Returns the data associated to the given document
* @private
* @param {Document} ownerDocument The document.
* @returns {Object} An object of data.
*/
function getExpandoData(ownerDocument) {
var data = expandoData[ownerDocument[expando]];
if (!data) {
data = {};
expanID++;
ownerDocument[expando] = expanID;
expandoData[expanID] = data;
}
return data;
}
/**
* returns a shived element for the given nodeName and document
* @memberOf html5
* @param {String} nodeName name of the element
* @param {Document} ownerDocument The context document.
* @returns {Object} The shived element.
*/
function createElement(nodeName, ownerDocument, data){
if (!ownerDocument) {
ownerDocument = document;
}
if(supportsUnknownElements){
return ownerDocument.createElement(nodeName);
}
if (!data) {
data = getExpandoData(ownerDocument);
}
var node;
if (data.cache[nodeName]) {
node = data.cache[nodeName].cloneNode();
} else if (saveClones.test(nodeName)) {
node = (data.cache[nodeName] = data.createElem(nodeName)).cloneNode();
} else {
node = data.createElem(nodeName);
}
// Avoid adding some elements to fragments in IE < 9 because
// * Attributes like `name` or `type` cannot be set/changed once an element
// is inserted into a document/fragment
// * Link elements with `src` attributes that are inaccessible, as with
// a 403 response, will cause the tab/window to crash
// * Script elements appended to fragments will execute when their `src`
// or `text` property is set
return node.canHaveChildren && !reSkip.test(nodeName) && !node.tagUrn ? data.frag.appendChild(node) : node;
}
/**
* returns a shived DocumentFragment for the given document
* @memberOf html5
* @param {Document} ownerDocument The context document.
* @returns {Object} The shived DocumentFragment.
*/
function createDocumentFragment(ownerDocument, data){
if (!ownerDocument) {
ownerDocument = document;
}
if(supportsUnknownElements){
return ownerDocument.createDocumentFragment();
}
data = data || getExpandoData(ownerDocument);
var clone = data.frag.cloneNode(),
i = 0,
elems = getElements(),
l = elems.length;
for(;i<l;i++){
clone.createElement(elems[i]);
}
return clone;
}
/**
* Shivs the `createElement` and `createDocumentFragment` methods of the document.
* @private
* @param {Document|DocumentFragment} ownerDocument The document.
* @param {Object} data of the document.
*/
function shivMethods(ownerDocument, data) {
if (!data.cache) {
data.cache = {};
data.createElem = ownerDocument.createElement;
data.createFrag = ownerDocument.createDocumentFragment;
data.frag = data.createFrag();
}
ownerDocument.createElement = function(nodeName) {
//abort shiv
if (!html5.shivMethods) {
return data.createElem(nodeName);
}
return createElement(nodeName, ownerDocument, data);
};
ownerDocument.createDocumentFragment = Function('h,f', 'return function(){' +
'var n=f.cloneNode(),c=n.createElement;' +
'h.shivMethods&&(' +
// unroll the `createElement` calls
getElements().join().replace(/[\w\-:]+/g, function(nodeName) {
data.createElem(nodeName);
data.frag.createElement(nodeName);
return 'c("' + nodeName + '")';
}) +
');return n}'
)(html5, data.frag);
}
/*--------------------------------------------------------------------------*/
/**
* Shivs the given document.
* @memberOf html5
* @param {Document} ownerDocument The document to shiv.
* @returns {Document} The shived document.
*/
function shivDocument(ownerDocument) {
if (!ownerDocument) {
ownerDocument = document;
}
var data = getExpandoData(ownerDocument);
if (html5.shivCSS && !supportsHtml5Styles && !data.hasCSS) {
data.hasCSS = !!addStyleSheet(ownerDocument,
// corrects block display not defined in IE6/7/8/9
'article,aside,dialog,figcaption,figure,footer,header,hgroup,main,nav,section{display:block}' +
// adds styling not present in IE6/7/8/9
'mark{background:#FF0;color:#000}' +
// hides non-rendered elements
'template{display:none}'
);
}
if (!supportsUnknownElements) {
shivMethods(ownerDocument, data);
}
return ownerDocument;
}
/*--------------------------------------------------------------------------*/
/**
* The `html5` object is exposed so that more elements can be shived and
* existing shiving can be detected on iframes.
* @type Object
* @example
*
* // options can be changed before the script is included
* html5 = { 'elements': 'mark section', 'shivCSS': false, 'shivMethods': false };
*/
var html5 = {
/**
* An array or space separated string of node names of the elements to shiv.
* @memberOf html5
* @type Array|String
*/
'elements': options.elements || 'abbr article aside audio bdi canvas data datalist details dialog figcaption figure footer header hgroup main mark meter nav output progress section summary template time video',
/**
* current version of html5shiv
*/
'version': version,
/**
* A flag to indicate that the HTML5 style sheet should be inserted.
* @memberOf html5
* @type Boolean
*/
'shivCSS': (options.shivCSS !== false),
/**
* Is equal to true if a browser supports creating unknown/HTML5 elements
* @memberOf html5
* @type boolean
*/
'supportsUnknownElements': supportsUnknownElements,
/**
* A flag to indicate that the document's `createElement` and `createDocumentFragment`
* methods should be overwritten.
* @memberOf html5
* @type Boolean
*/
'shivMethods': (options.shivMethods !== false),
/**
* A string to describe the type of `html5` object ("default" or "default print").
* @memberOf html5
* @type String
*/
'type': 'default',
// shivs the document according to the specified `html5` object options
'shivDocument': shivDocument,
//creates a shived element
createElement: createElement,
//creates a shived documentFragment
createDocumentFragment: createDocumentFragment
};
/*--------------------------------------------------------------------------*/
// expose html5
window.html5 = html5;
// shiv the document
shivDocument(document);
}(this, document));
把html5shiv.js在head里面引入，如下：
<!DOCTYPE HTML>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script type="text/javascript" src="js/html5shiv.js"></script>
<style type="text/css">
nav {
width:200px;
height:100px;
background:#f12;
}
</style>
</head>
<body>
<nav>123abc</nav>abc123
</body>
</html>
文章出处: 开源中国博客
