JavaScript widget boundaries: what ADsafe helps explain
Understand the difference between limiting a JavaScript API and isolating third-party code, using ADsafe's historical model as a starting point.
The JavaScript notebook
Practical explanations, with the historical context kept in view.
From the JavaScript notebook
Building a mediated DOM interface for guest code
Give guest code a narrow wrapper instead of the real DOM: a small original example, what it protects, and where it still leaks.
Content Security Policy and third-party scripts
What a Content Security Policy restricts for embedded widgets, what it leaves open, and why it complements rather than replaces isolation.
Reading the ADsafe widget template, part by part
A walk through the ADsafe widget template: the container div, ADSAFE.id, library scripts, ADSAFE.go and the rules that connect them.
Sandboxed iframes compared with the ADsafe approach
How the iframe sandbox attribute isolates a browsing context, and how that differs from ADsafe's restricted JavaScript subset and mediated DOM.
Why eval, this and global names are restricted in guest code
Why a restricted JavaScript subset such as ADsafe's forbids eval, this, global variables and dynamic property names, and what risk each rule addresses.