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World Congress 2025 • Aug 20, 2025 • Session details

Best of the Worst – the most awful anti-features in JavaScript, ranked!

Peter Kröner

Why do fundamentally broken JavaScript features remain permanently unfixed? Discover the bizarre anti-features forever trapped in the language's architecture by the strict rule of infinite backwards compatibility.

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#1 about 2 min

Evaluating the true impact of bad JavaScript features

Examining historically significant language quirks reveals deeper architectural flaws beyond simple type coercion jokes.

#2 about 5 min

Confounding logical checks using primitive wrapper objects

Constructing boolean and number primitives as objects accidentally bypasses logical operators and strict type enforcement checks.

#3 about 5 min

Bypassing variable shadowing with the function constructor

Executing strings as functions provides a reliable escape hatch for accessing globally shadowed system variables.

#4 about 10 min

Breaking static analysis via dynamic object environment records

The legacy with statement creates unpredictable scoping that neutralizes static analysis and degrades overall engine performance.

#5 about 6 min

Parsing integer pitfalls and the persistence of legacy flaws

The numerical string parser introduces hex guessing traps that remain unpatched in modern class object implementations.

#6 about 2 min

Rapid overview of minor frustrating web platform quirks

Rapidly traversing bizarre string routines and legacy document models illustrates the complexity of maintaining backwards compatibility.

Matching moments

2:37 min

Addressing the complaints about JavaScript as a programming language

Sasha Shynkevich · LIVE

3:29 min

Overview of extreme rules lawyering in JavaScript standards

Peter Kröner Peter Kröner · WWC Europe 2026

3:26 min

How heavy JavaScript payloads degrade browser performance and resilience

Chris Ferdinandi · JS Congress

4:09 min

Creating resilient applications relying on modern hardware integrations

Christian Liebel Christian Liebel · JS Congress

5:10 min

Evaluating the operational trade-offs of modern javascript frameworks

Chris Heilmann +2 · LIVE

7:04 min

Exploring browser limits with JavaScript golfing and weird hacks

Chris Heilmann +2 · LIVE

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