Result


コードはまだ実験的なもののようです。本当に簡易的なものだけど少ないコードで済むのは良いですね。

jQuery

// Pure JQuery Syntax Highlighter by Taufik Nurrohman
// Still an experimental :)
// https://plus.google.com/108949996304093815163/about

$(window).load(function() {
    $('pre').each(function() {
      //特定のキーワードをリスト化
        var list = "(true|false|null|main|in|endif|if|endfor|for|while|finally|var|new|function|do|return|void|else|break|catch|instanceof|with|throw|case|default|try|this|switch|continue|typeof|delete)",
            rep1 = new RegExp(list + " ", "ig"),
            rep2 = new RegExp(list + "( ?)<span", "ig"),
            $this = $(this);
        $this.html($this.html()
                  //各タグをclassを持ったspanで囲う
        .replace(/(<br>|\n)$/ig, "")
        .replace(/(\t)/ig, "    ")
        .replace(/&quot;/ig, "\"")
        .replace(/&#39;|&apos;/ig, "\'")
        .replace(/(.?)'(.*?)'/g, "$1<span class='str'>\'$2\'</span>")
        .replace(/(.?)"(.*?)"/g, "$1<span class='str'>\"$2\"</span>")
        .replace(/(.?)(""|'')/g, "$1<span class='value'>$2</span>")
        .replace(/(#[A-F0-9]{3,6})/ig, "<span class='hex'>$1</span>")
        .replace(/(\d+(?!(.*&lt;)))/g, "<span class='num'>$1</span>")
        .replace(/((#|\.)[\-_A-Z0-9]+)/ig, "<span class='selector'>$1</span>")
        .replace(/(\{|\}|\(|\)|\[|\])/g, "<span class='bracket'>$1</span>")
        .replace(/&lt;(.*?)&gt;/g, "<span class='tag'>&lt;$1&gt;</span>")
        .replace(/&lt;!--([\s\S]*?)--&gt;/gm, "<span class='comment'>&lt;!--$1--&gt;</span>")
        .replace(/\/\*([\s\S]*?)\*\//gm, "<span class='comment'>/*$1*/</span>")
        .replace(/[^\:]\/\/(.*)/g, "<span class='comment'>//$1</span>")
        .replace(/<\/span>\/(.*)\/([gim]+),( ?)<span class='str'>/g, "</span><span class='regexp'>/$1/$2</span>, <span class='str'>")
        .replace(rep1, "<span class='keyword'>$1</span> ")
        .replace(rep2, "<span class='keyword'>$1</span>$2<span")
        .replace(/function<\/span> (.[^<]*)<span/g, "function</span> <span class='name'>$1</span><span")
        .replace(/([\-_A-Z]+)(?=(\s+|)):(.(?!\{)*)/ig, "<span class='attribute'>$1</span>:$2$3")
        .replace(/h<span class='num'>([1-6])<\/span>/ig, "h$1")
        .replace(/!important/ig, "<mark class='important'>!important</mark>")
        .replace(/&lt;!(doctype)(.*)&gt;/ig, "<span class='doctype'>&lt;!$1$2&gt;</span>")
        .replace(/@<span class='attribute'>(import|page|media|charset|keyframes|font-face)<\/span>/ig, "@$1")
        .replace(/(@(import|page|media|charset|keyframes|font-face))/ig, "<span class='keyword'>$1</span>")
        .replace(/<span class='bracket'>\[<\/span>(.*)<span class='bracket'>\]<\/span>/ig, "<span class='array'>[$1]</span>")
        ).find('.str span, .regexp span, .comment span, .doctype span, .hex span, .array span, .url span').contents().unwrap();
        $this.append('<div class="the-num"></div>');

        // 行数をつける
        var num = $this.html().split(/\n|<br>/).length,
            count = 0;
        for (var i = 0; i < num; i++) {
            count = count + 1;
            $this.find('.the-num').append(count + '.<br/>');
        }
        $this.css('padding-left', $this.find('.the-num').outerWidth()+14);

    });
});

css

/*それぞれのコードをスタイル*/
pre .bracket   {color:darkblue;}
pre .tag,
pre .tag .keyword,
pre .tag .attribute {color:blue;}
pre .selector  {color:blue;}
pre .attribute,
pre .regexp    {color:darkorange;}
pre .str       {color:green;}
pre .tag .str  {color:brown;}
pre .keyword   {color:darkred;}
pre .comment   {font-style:italic;color:#999;}
pre .num,
pre .hex       {color:darkviolet;}
pre .name,
pre .important,
pre .array     {color:red;}
pre .important {background-color:yellow;}
pre .doctype   {color:magenta;}

html

<pre>&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
&lt;meta charset="utf-8"&gt;
&lt;title&gt;Sample Page&lt;/title&gt;
</pre>

via

http://www.dte.web.id/2012/06/syntax-highlighter-eksperimen.html