Create a handler that allows admins to insert HTML code into a webform page's header and footer

Problem/Motivation

To track a webform's events analytics and tracking services needs to insert custom JS snippets into a webform page's header and footer.

Proposed resolution

Create a handler that allows admins to insert HTML code into a page's header and footer based on a submissions states and conditional logic.

Because of the security implications of this handler, it will be implemented as an optional sub-module with dedicated permissions.

Remaining tasks

• Create webform_embed_code.module
• Create 'edit webform embed code'
• Create WebformEmbedCodeHandler
• Create 'webform_embed_code.manager' service.
• Implement hook_page_attachments()
• Implement hook_preprocess_html()
• Write handler config scheme
• Write handler template
• Create test form.
• Write tests.

Notes

• Anything can be inserted in a page's header, and footer including script tags and css.
• The security implications for this feature are the same as the webform module's JS/CSS injection.

User interface changes

New handler.

API changes

None

Data model changes

None