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World Congress 2026 Europe • Jul 9, 2026 • Session details

Extreme Rules Lawyering with the ECMAScript Specifications

Peter Kröner

What happens when you return a Promise directly from a class constructor? Dive into the ECMAScript specifications to exploit semantic loopholes and hijack fundamental JavaScript behaviors.

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#1 about 4 min

Overview of extreme rules lawyering in JavaScript standards

An introduction to reading web technology specifications and uncovering obscure JavaScript behavior.

#2 about 5 min

Contextual keywords and strict backward compatibility requirements

How browsers handle conditionally valid tokens to avoid breaking legacy code.

#3 about 3 min

Why JavaScript classes are actually just disguised functions

The technical reality that classes behave as function factories with an implicit return.

#4 about 6 min

Enforcing asynchronous initialization checks using class constructors

Using constructor return loopholes to yield promises and enforce safe object initialization.

#5 about 4 min

The technical illusion behind JavaScript private properties

Why private fields function differently from ordinary properties by relying on isolated internal slots.

#6 about 4 min

How standard operations map to object internal methods

Exploring how language syntax triggers underlying internal object methods like delete operations.

#7 about 3 min

Creating and manipulating exotic objects with Proxies

Intercepting core operations to attach custom logic and build specialized exotic objects.

#8 about 4 min

Observability limitations and proxy clashes with private properties

How private fields entirely bypass internal operations and break standard proxy interceptions.

#9 about 3 min

Final conclusions and Q&A on JavaScript specifications

A summary of specification quirks and answers to questions about promise syntax.

Matching moments

1:04 min

Evaluating the true impact of bad JavaScript features

Peter Kröner Peter Kröner · WWC 2025

2:37 min

Addressing the complaints about JavaScript as a programming language

Sasha Shynkevich · LIVE

7:04 min

Exploring browser limits with JavaScript golfing and weird hacks

Chris Heilmann +2 · LIVE

2:00 min

Understanding core browser technologies and framework syntax sugar

Sasha Shynkevich · LIVE

3:26 min

Handling edge cases surrounding syntax scope and formatting fallbacks

Ire Aderinokun · WWC 2022

1:11 min

Fundamentals of JavaScript minification and internal variable mangling

Stephen Cooper Stephen Cooper · WWC 2025

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