Tweaks to rnocache

JavaScript performance comparison

Revision 7 of this test case created by Charles McNulty

Info

In jQuery 1.6.x and previous the .html() function uses an variable called rnocache for determining problematic html tags for both caching and for the use of innerHtml. The problem is that these two purposes share very little overlap, and conflating them results in not using innerHtml in places where it's perfectly safe, and much faster. A fix for this has gone into jQuery 1.7.

For discussion and bug see:

To implement the test, I extend jquery 1.7 with a .html2() function which is a direct copy of the version of .html() 1.7 directly before the patch which addresses this issue.

In 1.7 there is a new variable,

rnoInnerhtml = /<script|<style/i

which I use in place of rnocache within .html(). This change allows me to then copy a select box using innerHTML rather than .empty().append() which results in some rather large speed increases.

Preparation code

<script src="//code.jquery.com/jquery-1.7b1.js"></script>
<div>Original: <div id="source"><select id="test_select" name="test_select">
        <option label="1">0</option>
        <option label="1">1</option>
        <option label="2">2</option>
        <option label="3" selected="selected">3</option>
        <option label="4">4</option>
        <option label="1">5</option>
        <option label="2">6</option>
        <option label="3">7</option>
        <option label="4">8</option>
        <option label="1">9</option>
</select>
</div></div>
Following two selects should be identical:
<div>Unoptimized copy: <div id="destination"></div></div>
<div>Optimized copy:<div id="destination2"></div></div>
<script>
  (function($) {
 
  var rinlinejQuery = / jQuery\d+="(?:\d+|null)"/g,
        rleadingWhitespace = /^\s+/,
        rxhtmlTag = /<(?!area|br|col|embed|hr|img|input|link|meta|param)(([\w:]+)[^>]*)\/>/ig,
        rtagName = /<([\w:]+)/,
        rtbody = /<tbody/i,
        rhtml = /<|&#?\w+;/,
        rnocache = /<(?:script|object|embed|option|style)/i,
        // checked="checked" or checked
        rchecked = /checked\s*(?:[^=]|=\s*.checked.)/i,
        rscriptType = /\/(java|ecma)script/i,
        rcleanScript = /^\s*<!(?:\[CDATA\[|\-\-)/,
        wrapMap = {
                option: [ 1, "<select multiple='multiple'>", "</select>" ],
                legend: [ 1, "<fieldset>", "</fieldset>" ],
                thead: [ 1, "<table>", "</table>" ],
                tr: [ 2, "<table><tbody>", "</tbody></table>" ],
                td: [ 3, "<table><tbody><tr>", "</tr></tbody></table>" ],
                col: [ 2, "<table><tbody></tbody><colgroup>", "</colgroup></table>" ],
                area: [ 1, "<map>", "</map>" ],
                _default: [ 0, "", "" ]
        },
        safeFragment = (function() {
                var nodeNames = (
                        "abbr article aside audio canvas datalist details figcaption figure footer " +
                        "header hgroup mark meter nav output progress section summary time video"
                ).split( " " ),
                safeFrag = document.createDocumentFragment();
 
                if ( safeFrag.createElement ) {
                        while ( nodeNames.length ) {
                                safeFrag.createElement(
                                        nodeNames.pop()
                                );
                        }
                }
                return safeFrag;
        })();
 
  wrapMap.optgroup = wrapMap.option;
  wrapMap.tbody = wrapMap.tfoot = wrapMap.colgroup = wrapMap.caption = wrapMap.thead;
  wrapMap.th = wrapMap.td;
 
  // IE can't serialize <link> and <script> tags normally
  if ( !jQuery.support.htmlSerialize ) {
        wrapMap._default = [ 1, "div<div>", "</div>" ];
  }
 
   $.fn.html2 = function(value) {
 
                if ( value === undefined ) {
                        return this[0] && this[0].nodeType === 1 ?
                                this[0].innerHTML.replace(rinlinejQuery, "") :
                                null;
 
                // See if we can take a shortcut and just use innerHTML
                } else if ( typeof value === "string" && !rnocache.test( value ) &&
                        (jQuery.support.leadingWhitespace || !rleadingWhitespace.test( value )) &&
                        !wrapMap[ (rtagName.exec( value ) || ["", ""])[1].toLowerCase() ] ) {
 
                        value = value.replace(rxhtmlTag, "<$1></$2>");
 
                        try {
                                for ( var i = 0, l = this.length; i < l; i++ ) {
                                        // Remove element nodes and prevent memory leaks
                                        if ( this[i].nodeType === 1 ) {
                                                jQuery.cleanData( this[i].getElementsByTagName("*") );
                                                this[i].innerHTML = value;
                                        }
                                }
 
                        // If using innerHTML throws an exception, use the fallback method
                        } catch(e) {
                                this.empty().append( value );
                        }
 
                } else if ( jQuery.isFunction( value ) ) {
                        this.each(function(i){
                                var self = jQuery( this );
 
                                self.html( value.call(this, i, self.html()) );
                        });
 
                } else {
                        this.empty().append( value );
                }
 
                return this;
 
   };
  })(jQuery);
 
  var template = $("#source").html();
</script>

Preparation code output

Original:
Following two selects should be identical:
Unoptimized copy:
Optimized copy:

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
using innerHTML optimized regex
$("#destination").html(template);
pending…
using standard nocache (no optimization)
$("#destination2").html2(template);
pending…

Compare results of other browsers

Revisions

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