Fiddle: http://jsfiddle.net/JFSKe/6/
DocumentFragment doesn't implement DOM methods. Using document.createElement in conjunction with innerHTML removes the <head> and <body> tags (even when the created element is a root element, <html>). Therefore, the solution should be sought elsewhere. I have created a cross-browser string-to-DOM function, which makes use of an invisible inline-frame.
All external resources and scripts will be disabled. See Explanation of the code for more information.
Code
/*
@param String html The string with HTML which has be converted to a DOM object
@param func callback (optional) Callback(HTMLDocument doc, function destroy)
@returns undefined if callback exists, else: Object
HTMLDocument doc DOM fetched from Parameter:html
function destroy Removes HTMLDocument doc. */
function string2dom(html, callback){
/* Sanitise the string */
html = sanitiseHTML(html); /*Defined at the bottom of the answer*/
/* Create an IFrame */
var iframe = document.createElement("iframe");
iframe.style.display = "none";
document.body.appendChild(iframe);
var doc = iframe.contentDocument || iframe.contentWindow.document;
doc.open();
doc.write(html);
doc.close();
function destroy(){
iframe.parentNode.removeChild(iframe);
}
if(callback) callback(doc, destroy);
else return {"doc": doc, "destroy": destroy};
}
/* @name sanitiseHTML
@param String html A string representing HTML code
@return String A new string, fully stripped of external resources.
All "external" attributes (href, src) are prefixed by data- */
function sanitiseHTML(html){
/* Adds a <!-"'--> before every matched tag, so that unterminated quotes
aren't preventing the browser from splitting a tag. Test case:
'<input style="foo;b:url(0);><input onclick="<input type=button onclick="too() href=;>">' */
var prefix = "<!--"'-->";
/*Attributes should not be prefixed by these characters. This list is not
complete, but will be sufficient for this function.
(see http://www.w3.org/TR/REC-xml/#NT-NameChar) */
var att = "[^-a-z0-9:._]";
var tag = "<[a-z]";
var any = "(?:[^<>"']*(?:"[^"]*"|'[^']*'))*?[^<>]*";
var etag = "(?:>|(?=<))";
/*
@name ae
@description Converts a given string in a sequence of the
original input and the HTML entity
@param String string String to convert
*/
var entityEnd = "(?:;|(?!\d))";
var ents = {" ":"(?:\s| ?|�*32"+entityEnd+"|�*20"+entityEnd+")",
"(":"(?:\(|�*40"+entityEnd+"|�*28"+entityEnd+")",
")":"(?:\)|�*41"+entityEnd+"|�*29"+entityEnd+")",
".":"(?:\.|�*46"+entityEnd+"|�*2e"+entityEnd+")"};
/*Placeholder to avoid tricky filter-circumventing methods*/
var charMap = {};
var s = ents[" "]+"*"; /* Short-hand space */
/* Important: Must be pre- and postfixed by < and >. RE matches a whole tag! */
function ae(string){
var all_chars_lowercase = string.toLowerCase();
if(ents[string]) return ents[string];
var all_chars_uppercase = string.toUpperCase();
var RE_res = "";
for(var i=0; i<string.length; i++){
var char_lowercase = all_chars_lowercase.charAt(i);
if(charMap[char_lowercase]){
RE_res += charMap[char_lowercase];
continue;
}
var char_uppercase = all_chars_uppercase.charAt(i);
var RE_sub = [char_lowercase];
RE_sub.push("�*" + char_lowercase.charCodeAt(0) + entityEnd);
RE_sub.push("�*" + char_lowercase.charCodeAt(0).toString(16) + entityEnd);
if(char_lowercase != char_uppercase){
RE_sub.push("�*" + char_uppercase.charCodeAt(0) + entityEnd);
RE_sub.push("�*" + char_uppercase.charCodeAt(0).toString(16) + entityEnd);
}
RE_sub = "(?:" + RE_sub.join("|") + ")";
RE_res += (charMap[char_lowercase] = RE_sub);
}
return(ents[string] = RE_res);
}
/*
@name by
@description second argument for the replace function.
*/
function by(match, group1, group2){
/* Adds a data-prefix before every external pointer */
return group1 + "data-" + group2
}
/*
@name cr
@description Selects a HTML element and performs a
search-and-replace on attributes
@param String selector HTML substring to match
@param String attribute RegExp-escaped; HTML element attribute to match
@param String marker Optional RegExp-escaped; marks the prefix
@param String delimiter Optional RegExp escaped; non-quote delimiters
@param String end Optional RegExp-escaped; forces the match to
end before an occurence of <end> when
quotes are missing
*/
function cr(selector, attribute, marker, delimiter, end){
if(typeof selector == "string") selector = new RegExp(selector, "gi");
marker = typeof marker == "string" ? marker : "\s*=";
delimiter = typeof delimiter == "string" ? delimiter : "";
end = typeof end == "string" ? end : "";
var is_end = end && "?";
var re1 = new RegExp("("+att+")("+attribute+marker+"(?:\s*"[^""+delimiter+"]*"|\s*'[^'"+delimiter+"]*'|[^\s"+delimiter+"]+"+is_end+")"+end+")", "gi");
html = html.replace(selector, function(match){
return prefix + match.replace(re1, by);
});
}
/*
@name cri
@description Selects an attribute of a HTML element, and
performs a search-and-replace on certain values
@param String selector HTML element to match
@param String attribute RegExp-escaped; HTML element attribute to match
@param String front RegExp-escaped; attribute value, prefix to match
@param String flags Optional RegExp flags, default "gi"
@param String delimiter Optional RegExp-escaped; non-quote delimiters
@param String end Optional RegExp-escaped; forces the match to
end before an occurence of <end> when
quotes are missing
*/
function cri(selector, attribute, front, flags, delimiter, end){
if(typeof selector == "string") selector = new RegExp(selector, "gi");
flags = typeof flags == "string" ? flags : "gi";
var re1 = new RegExp("("+att+attribute+"\s*=)((?:\s*"[^"]*"|\s*'[^']*'|[^\s>]+))", "gi");
end = typeof end == "string" ? end + ")" : ")";
var at1 = new RegExp('(")('+front+'[^"]+")', flags);
var at2 = new RegExp("(')("+front+"[^']+')", flags);
var at3 = new RegExp("()("+front+'(?:"[^"]+"|'[^']+'|(?:(?!'+delimiter+').)+)'+end, flags);
var handleAttr = function(match, g1, g2){
if(g2.charAt(0) == '"') return g1+g2.replace(at1, by);
if(g2.charAt(0) == "'") return g1+g2.replace(at2, by);
return g1+g2.replace(at3, by);
};
html = html.replace(selector, function(match){
return prefix + match.replace(re1, handleAttr);
});
}
/* <meta http-equiv=refresh content=" ; url= " > */
html = html.replace(new RegExp("<meta"+any+att+"http-equiv\s*=\s*(?:""+ae("refresh")+"""+any+etag+"|'"+ae("refresh")+"'"+any+etag+"|"+ae("refresh")+"(?:"+ae(" ")+any+etag+"|"+etag+"))", "gi"), "<!-- meta http-equiv=refresh stripped-->");
/* Stripping all scripts */
html = html.replace(new RegExp("<script"+any+">\s*//\s*<\[CDATA\[[\S\s]*?]]>\s*</script[^>]*>", "gi"), "<!--CDATA script-->");
html = html.replace(/<script[Ss]+?</scripts*>/gi, "<!--Non-CDATA script-->");
cr(tag+any+att+"on[-a-z0-9:_.]+="+any+etag, "on[-a-z0-9:_.]+"); /* Event listeners */
cr(tag+any+att+"href\s*="+any+etag, "href"); /* Linked elements */
cr(tag+any+att+"src\s*="+any+etag, "src"); /* Embedded elements */
cr("<object"+any+att+"data\s*="+any+etag, "data"); /* <object data= > */
cr("<applet"+any+att+"codebase\s*="+any+etag, "codebase"); /* <applet codebase= > */
/* <param name=movie value= >*/
cr("<param"+any+att+"name\s*=\s*(?:""+ae("movie")+"""+any+etag+"|'"+ae("movie")+"'"+any+etag+"|"+ae("movie")+"(?:"+ae(" ")+any+etag+"|"+etag+"))", "value");
/* <style> and < style= > url()*/
cr(/<style[^>]*>(?:[^"']*(?:"[^"]*"|'[^']*'))*?[^'"]*(?:</style|$)/gi, "url", "\s*\(\s*", "", "\s*\)");
cri(tag+any+att+"style\s*="+any+etag, "style", ae("url")+s+ae("(")+s, 0, s+ae(")"), ae(")"));
/* IE7- CSS expression() */
cr(/<style[^>]*>(?:[^"']*(?:"[^"]*"|'[^']*'))*?[^'"]*(?:</style|$)/gi, "expression", "\s*\(\s*", "", "\s*\)");
cri(tag+any+att+"style\s*="+any+etag, "style", ae("expression")+s+ae("(")+s, 0, s+ae(")"), ae(")"));
return html.replace(new RegExp("(?:"+prefix+")+", "g"), prefix);
}
Explanation of the code
The sanitiseHTML function is based on my replace_all_rel_by_abs function (see this answer). The sanitiseHTML function is completely rewritten though, in order to achieve maximum efficiency and reliability.
Additionally, a new set of RegExps are added to remove all scripts and event handlers (including CSS expression(), IE7-). To make sure that all tags are parsed as expected, the adjusted tags are prefixed by <!--'"-->. This prefix is necessary to correctly parse nested "event handlers" in conjunction with unterminated quotes: <a id="><input onclick="<div onmousemove=evil()>">.
These RegExps are dynamically created using an internal function cr/cri (Create Replace [Inline]). These functions accept a list of arguments, and create and execute an advanced RE replacement. To make sure that HTML entities aren't breaking a RegExp (refresh in <meta http-equiv=refresh> could be written in various ways), the dynamically created RegExps are partially constructed by function ae (Any Entity).
The actual replacements are done by function by (replace by). In this implementation, by adds data- before all matched attributes.
- All
<script>//<[CDATA[ .. //]]></script> occurrences are striped. This step is necessary, because CDATA sections allow </script> strings inside the code. After this replacement has been executed, it's safe to go to the next replacement:
- The remaining
<script>...</script>
