This blog post describes the ECMAScript proposal “ShadowRealm API” by Dave Herman, Caridy Patiño, Mark S. Miller, Leo Balter, and Rick Waldron. Class ShadowRealm provides a new way of evaluating code at runtime – think eval() but better: Each instance has its own global JavaScript scope. Code is evaluated in that scope. If it changes global data, that only affects the ShadowRealm, but not the real global data.
