About this reference
Studying ADsafe? This independent reference explains its historical JavaScript restrictions and widget interface through newly written guides.
What ADsafe tried to constrain
ADsafe addressed a specific problem: allowing a guest widget to interact with its own part of a page while limiting access to the surrounding document. Its design combined restrictions on JavaScript with a runtime that mediated access to page elements.
The original project is associated with Douglas Crockford. This website is edited by ADsafe Editorial as an independent educational reference. It does not represent the original author, claim his endorsement, or offer an official continuation of his work.
How we use historical sources
The guides draw on historical documentation and the original public source repository. Explanations and interactive examples on this site are newly written. Historical file paths remain available so older references lead to useful material.
The legacy runtime is offered separately for historical study with its source notice intact. Our pages do not load it. A historical implementation should not be treated as a reviewed security boundary for a new application.
Start with the design
Read Widget Structure for the relationship between a host page and guest code, then DOM API for the mediated document interface.
Primary source: the original ADsafe repository.