<ScriptBlock>

<ScriptBlock> registers a JavaScript block (or an external script file) with the hosting page so it ends up in the head, body-top, or body-bottom of the rendered HTML. The block is identified by ScriptId, which lets the same script appear in multiple forms or views without rendering twice when RegisterOnce="True".

The actual <script> tag goes between the opening and closing <ScriptBlock> tags — wrap it in a CDATA section if your script contains characters that confuse the XML parser. With BlockType="HeadScript" the block can carry <style>, <link> and <meta> tags as well.

The content is plain markup plus tokens; field, system and expression tokens are replaced before the block is registered. Do not place other XMP controls inside a <ScriptBlock> — the block only registers the markup before the first nested control and drops the rest without an error. Use an expression token for anything computed, such as [[=Format(DueDate, 'yyyy-MM-dd')]].

Example

<AddForm>
  <ScriptBlock ScriptId="AlertScripts" RegisterOnce="True">
    <script type="text/javascript">
      function helloWorld() {
        alert('Hello World');
      }
      function goodbyeWorld() {
        alert('Goodbye Cruel World');
      }
      function showMessage(sMessage) {
        alert(sMessage);
      }
    </script>
  </ScriptBlock>
  <table>
    <tr>
      <td>
        <a href="#" onclick="helloWorld();">Hello World</a><br />
        <a href="#" onclick="goodbyeWorld();">Goodbye</a><br />
        <a href="#" onclick="showMessage('Hello and Goodbye');">Show Message</a>
      </td>
    </tr>
  </table>
</AddForm>

Properties

Property	Values	Default	Description
ScriptId *	string		Unique identifier used to deduplicate the script across the page
BlockType	ClientScript StartupScript HeadScript ClientScriptInclude	ClientScript	Where in the page the script is rendered
RegisterOnce	True False	False	When True, skip registration if the same ScriptId is already on the page
Url	URL		Used only with BlockType="ClientScriptInclude" — the path to the external .js file
If	expression		When set and the expression is false, the script is not registered (since v5.0)

* Required property

Property Details

• ScriptId: A page-wide unique identifier. When RegisterOnce="True", XMP checks whether a script with this ID has already been registered (by another <ScriptBlock>, another module, or DNN itself) and skips this block if so. Choose names specific enough to avoid collisions — "AcmeXmpFormHelpers" is safer than "helpers".

• BlockType: Where the script lands in the rendered HTML.

  Value	Location
  ClientScript (default)	Near the top of the page body
  StartupScript	Near the bottom of the page body — runs after most of the DOM is in place
  HeadScript	Inside the page's <head>
  ClientScriptInclude	Renders a <script src="..."> reference to the file at Url

• RegisterOnce: When True, the block is registered only if no other block with the same ScriptId is already on the page. Use this when the same form (or several forms sharing a helper) might be rendered more than once on a single page.

  The setting matters for BlockType="HeadScript": blocks are registered in the order they appear, the first block registered under a ScriptId wins, and later blocks with the same ScriptId are skipped. Without RegisterOnce, a second HeadScript block with the same ScriptId is written into the head again. For the other block types ASP.NET already keys each registration by ScriptId, so a duplicate is never emitted either way.

• Url: When BlockType="ClientScriptInclude", the path to the external .js file. Tilde (~) is supported for site-root-relative paths. Ignored for other block types.

  <ScriptBlock ScriptId="AcmeUtils"
               BlockType="ClientScriptInclude"
               Url="~/scripts/acme-utils.js"
               RegisterOnce="True" />

• If: Decides whether the block is registered at all. Evaluated when the form renders, after tokens have been replaced. When the property is omitted, the block is always registered (the v4.x behavior). Otherwise:

  If value	Result
  empty	not registered
  false or 0 (any casing)	not registered
  a token mixed with other text (never resolves — see below)	not registered
  anything else	registered

  If is a simple on/off switch: it does not compare values, so = or <> inside the value are just characters. A bare field token is the easiest "has a value" test (If='[[ReturnUrl]]'); for a real comparison, use an expression token that returns true or false:

  <ScriptBlock ScriptId="MemberScripts" If="[[=If(${User:ID} > 0, 'true', 'false')]]">
    <script>console.log('member scripts loaded');</script>
  </ScriptBlock>

  Do not mix a token with literal text

  If="[[Status]] = Active" never registers. ASP.NET only resolves a token when it is the whole attribute value, so the comparison never sees the field's value, and <ScriptBlock> treats the unresolved text as "off". Put the comparison inside the expression token instead: If="[[=If(Status = 'Active', 'true', 'false')]]". This differs from form actions such as <Redirect If> and <Email SendIf>, which do accept [[Field]] = value because their tokens are replaced as text when the form is submitted.

  For head tags that depend on data — a fallback chain of <meta> tags, for example — see Conditional Content in the Head on the view-side control. The same patterns apply to a form's <ScriptBlock>.