Add character to empty html tags with c# and regex

Question

I want to find all empty HTML tags in a string, eg:

<div></div>
<span>test</span>
<a></a>

and add a space or a character to all of the empty tags in that string:

<div>something</div>
<span>test</span>
<a>something</a>

I've got an regex that matches all empty tags, but I'm not sure what's the best way replace the tags.

Regex:

<(\w+)(?:\s+\w+="[^"]+(?:"\$[^"]+"[^"]+)?")*>\s*</\1>

regex is not overkill. it is "underkill" :) Use a HTML/XML parser and interate over the DOM tree - this'll save you a lot of pain. — tessi
– tessi, Commented Jul 26, 2013 at 8:58
From what I've read the agilitypack can mess up the rest of the html making "fixes" to certain tags like <img />.. — ffffff01
– ffffff01, Commented Jul 26, 2013 at 8:59

Anirudha · Accepted Answer · 2013-07-26 09:23:26Z

3

Use HtmlAgilityPack

HtmlDocument doc = new HtmlDocument();
doc.LoadHtml(html);
foreach(HtmlNode node in doc.DocumentElement.SelectNodes("//*").Where(x=>x.InnerText==""))
{
       node.ParentNode.ReplaceChild(HtmlTextNode.CreateNode(input), node);
}
doc.Save(yourFile);

edited Jul 26, 2013 at 9:23

answered Jul 26, 2013 at 9:07

Anirudha

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3 Comments

ffffff01 Over a year ago

What If I dont got a complete html document? I just have a small part of a larger document and I just want to replace some tags.. Still the way to go? I feel like the crowd just have decided that if HTML and Regex is mencioned in a question HTML parser is the only option...

Anirudha Over a year ago

@f01 No matter in what form your html is in..be it incomplete,no end tags!,not an html!!! this parser would still work perfectly without any issues..

Anirudha Over a year ago

@f01 you could use a regex like (?<=<.*?[^/]>)(?=</.*?>) and replace it with something.. BUT i can give you 1000 cases where you would break your application

animuson · Accepted Answer · 2014-05-23 23:11:09Z

Description

Handling this via regex is probably not the best way to go, however because there may be reasons for using a regular expression such as "I'm not allowed to install HTMLAgilityPack" then this expression will:

find all tags which are simply open tag followed by a close tag
will avoid many of the edge cases that make pattern matching in HTML with regex difficult

Regex: (<(\w+)(?=\s|>)(?:[^'">=]*|='[^']*'|="[^"]*"|=[^'"][^\s>]*)*>)(<\/\2>)

Replace with: $1~~~NewValue~~~$3

enter image description here

Example

Live Demo

Sample Text

Note the first line has some really difficult edge cases

<a onmouseover=' str=" <a></a> " ; if ( 6 > 4 ) { funDoSomething(str); } '></a>
<div></div>
<span>test</span>
<a></a>

Text After Replacement

<a onmouseover=' str=" <a></a> " ; if ( 6 > 4 ) { funDoSomething(str); } '>~~~NewValue~~~</a>
<div>~~~NewValue~~~</div>
<span>test</span>
<a>~~~NewValue~~~</a>

Community · Accepted Answer · 2017-05-23 11:49:14Z

0

Use Html Agility Pack for Html Parsing never regex.

edited May 23, 2017 at 11:49

CommunityBot

11 silver badge

answered Jul 26, 2013 at 9:00

Raidri

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1 Comment

Ro Yo Mi Over a year ago

-1 because your proposed solution doesn't really provide an answer to the question. At best this is some vague direction to a rather specific request.

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