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The article discusses the withdrawal of Tuples and Records from the ES2025 standard due to performance and implementation challenges. It highlights the core issues that led to this decision, including unrealistic performance expectations and engine implementation difficulties. The proposal, which aimed to introduce native immutable data structures, was stuck at Stage 2 for an extended period and was officially withdrawn in April 2025. This decision reflects a broader shift in TC39’s approach to language evolution, emphasizing performance realism and cross-engine compatibility. Guhaprasaanth Nandagopal, the author, provides an in-depth analysis of the technical and design considerations that shaped this outcome.

Key facts

• Tuples and Records were withdrawn from the ES2025 standard due to performance and engine implementation challenges.
• The proposal aimed to introduce native immutable data structures with structural equality and memory efficiency.
• JavaScript engines faced significant difficulties in implementing structural equality for Tuples and Records.
• The TC39 committee decided not to pursue alternative approaches that would deviate from the original vision of the proposal.
• The withdrawal highlights the importance of balancing developer expectations with the practical constraints of JavaScript engine implementation.