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Enforce Anchor Target TBB

This week's TBB is Enforce Anchor Target TBB. The functionality is to enforce a 'system-wide' anchor target policy. Namely, any fully qualified URLs should open in a new (_blank) target browser window. All other (relative) URLs should open in the same target. More specifically, if there is a target specified for a relative URL, remove it.

Enforce Anchor Target TBB
·    Template in .NET Assembly
Used to:
·    Enforces a certain “target” attribute for the anchor tags depending on their “href” attribute value;
This generic TBB expects an Item called “Output” in the Package.
It parses the Output looking for anchor <a> tags. If the anchor’s “href” attribute is a fully qualified URL (starts with “http://” or “https://”), then it adds/replaces “target” attribute with value “_blank”. Otherwise, it removes the “target” attribute, if present.
Finally the transformed Output is saved back into the Package.
Applicable to
Any template where an Item called ‘Output’ exists in the Package

The Code

[TcmTemplateTitle("Enforce Anchor Target TBB")]
public class EnforceAnchorTarget : ITemplate {

    private const string ANCHOR_REG_EXP = "<a[^>]*>";
    private readonly Regex imgRegExp = new Regex(ANCHOR_REG_EXP, RegexOptions.IgnoreCase);
    private readonly TemplatingLogger log = TemplatingLogger.GetLogger(typeof(EnforceAnchorTarget));

    public void Transform(Engine engine, Package package) {
        GenericUtils utils = new GenericUtils();
        Item outputItem = package.GetByName(Package.OutputName);
        string xhtml = outputItem.GetAsString();

        foreach (Match match in GetAnchorTags(xhtml)) {
            string anchorHtmlTag = match.Value;
            string anchorHref = utils.GetHtmlTagAttributeValue("href", anchorHtmlTag);
            if (anchorHref == null) // anchor without an href

            string target = anchorHref.ToLower();
            if (target.StartsWith("http://") || target.StartsWith("https://")) {
                utils.SetHtmlTagAttribute("target", "_blank", ref anchorHtmlTag);
            } else {
                utils.RemoveHtmlTagAttribute("target", ref anchorHtmlTag);

            xhtml = xhtml.Replace(match.Value, anchorHtmlTag);


    private MatchCollection GetAnchorTags(string xhtml) {
        return imgRegExp.Matches(xhtml);


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