Regular expression- add target="blank" to all tag links in my content

Question

Can some one help me create a regular expression in C#.net to add target="_blank" to all <a> tag links in my content?

If the link already has a target set then replace it with "_blank". The purpose is to open all links in my content in a new window.

Appreciate your help

-dotnet rocks

dotnetrocks, but html parsing with regex don't http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags — Amarghosh, May 11 '10 at 04:43
Looking at the [specification for XML](http://www.w3.org/TR/2006/REC-xml11-20060816/#sec-starttags), this task might be possible for valid XHTML input. But it will look ugly. — Christian Semrau, May 14 '10 at 21:30
A simple regex would probably match inside comments and CDATA areas, which might or might not be a problem for you. These complications are the reason why here on Stack Overflow one usually gets a certain link as an answer for "parse HTML with regex" questions. — Christian Semrau, May 14 '10 at 21:34

score 10 · Answer 1 · edited Nov 27 '17 at 13:13

10

There are a lot of mentions regarding not to use regex when parsing HTML, so you could use Html Agility Pack for this:

HtmlDocument document = new HtmlDocument();
document.LoadHtml(yourHtml);

var links = document.DocumentNode.SelectNodes("//a");
foreach (HtmlNode link in links)
{
    if (link.Attributes["target"] != null)
    {
        link.Attributes["target"].Value = "_blank";
    }
    else
    {
        link.Attributes.Add("target", "_blank");
    }
}

this will add(or replace if necessary) target='_blank' to all the anchors in your document.

edited Nov 27 '17 at 13:13

carla

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answered Apr 23 '11 at 06:59

Oleks

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Then use var newHtml = document.DocumentNode.OuterHtml; – chrisb Oct 22 '15 at 12:53

score 7 · Answer 2 · edited Jul 07 '11 at 07:49

7

RegEx.Replace(inputString, "<(a)([^>]+)>", "<$1 target=""_blank""$2>")

It will add target also in those anchor tags which already have target present

edited Jul 07 '11 at 07:49

Edwin de Koning

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answered Jul 06 '11 at 09:33

Avinash Nigam

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Nice solution. I just changed the regex to following: RegEx.Replace(input, "<(a)([^>]+)>", "<$1 target=\"_blank\"$2>"); The only change is that I use escape before the double quotes insisde the regex replace, otherwise I get compile error. – Hallgeir Engen Feb 07 '13 at 09:48
1

Wouldn't this screw up all other tags starting with a? , i.e. . And why bother looking for the closing of the tag if you will add the target attribute anyway? Wouldn't RegEx.Replace(inputString, " – Michiel Apr 29 '13 at 09:15
1

I came up two regexps in sequence to achieve this. Note - I'm using JS. Remove target if it exists `result = result.replace(/(]*)(target="[^"]*")([^>]*>)/gi, '$1$3');`, add new target="_blank" `result = result.replace(/(]*)(>)/gi, '$1 target="_blank"$2');` – Carl di Ortus Apr 12 '18 at 11:21

score 2 · Answer 3 · answered Mar 26 '15 at 22:58

I did this with an extension method similar to the approach Alex showed. The method:

// Return the input string with all parsed HTML links having the "target" attribute set to specified value
// Links without a target attribute will have the attribute added, existing attributes values are updated
public static string SetHtmlLinkTargetAttribute(this string inputHtmlString, string target)
{
    var htmlContent = new HtmlDocument();
    htmlContent.LoadHtml(inputHtmlString);

    // Parse HTML content for links
    var links = htmlContent.DocumentNode.SelectNodes("//a");
    foreach (var link in links)
    {
        link.SetAttributeValue("target", target);
    }

    return htmlContent.DocumentNode.OuterHtml;
}

And using it to clean up my links:

// Enforce targets for links as "_blank" to open in new window
asset.Description = asset.Description.SetHtmlLinkTargetAttribute("_blank");

score 0 · Answer 4 · answered May 21 '10 at 18:38

0

RegEx.Replace(inputString, "<(a)([^>]+)>", "<$1 target=""_blank""$2>")

answered May 21 '10 at 18:38

Brandon Montgomery

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Good quick answer, but you don't account for target="_blank" or target="something else" already being in the regex. Something to think about. – Platinum Azure May 21 '10 at 18:41

Regular expression- add target="blank" to all tag links in my content

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