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Page Contributions

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Lets components, macros, and processors contribute content to the response HTML header and/or footer.

Only available in the Site Engine

Introduction

Some pages and applications require specific scripts to be available within the HTML response of a page, typically placed within a specific location of the markup such as in the <head> section, or close to the body end tag.

Example use cases are:

  • Let a part contribute JavaScript to the page’s <head> section.

  • Let a part contribute custom CSS to the <head> of that page.

  • A layout might add a JavaScript tracker to the end of the <body> of the page.

Page contributions will only be triggered if the response type is text/html (which is the default)

There are four positions in the result HTML where contributed content can be inserted:

headBegin

After the <head> opening tag.

headEnd

Before the </head> closing tag.

bodyBegin

After the <body> opening tag.

bodyEnd

Before the </body> closing tag.

Usage

The component or controller must add a pageContributions property in the HTTP response object.

Sample controller return adding a script element to headEnd.

return {
  body: '<p>Some markup</p>',
  pageContributions: {
    headEnd: [
      "<script>My script</script>"
    ]
  }
};

Changing the headEnd to one of the other possible positions will affect where the code you contributed is merged in the response markup.

Sample with multiple contributions 
return {
  "body": "<div>...</div>",
  "pageContributions": {
    "headEnd": "value",
    "bodyEnd": [
      "value1", "value2"
    ]
  }
};

  • Page Contributions are optional.

  • Contribution values are treated as plain text.

  • Values must be unique within each injection point, duplicates will be truncated.

  • If the target tag does not exist in the response body, the contribution will be ignored. I.e. if there is no <head> tag, the contributions to headBegin and headEnd will be ignored.

  • For consistency, all positions are automatically treated arrays in the aggregated response object, even if there is only a single value.

Contribution merging

Page contributions are merged into the response markup during a specific step in the site engine, called Contributions filter. It occurs after page processors and before the site filters.

Duplicate page contributions will automatically be removed, so developers do not have to worry about this.

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