Software Engineering Radio - the podcast for professional software developers

SE Radio 718: Will Sentance on JS Modernization

4 snips
Apr 29, 2026
Will Sentance, educator and Codesmith co-founder who teaches advanced JavaScript, explores JavaScript’s growth from a simple script language to the web’s backbone. He discusses backward-compatibility constraints, how community patterns become standards, engine optimizations like monomorphic object shapes, practical coding patterns for performance, and the benefits and risks of LLMs for developer understanding.
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ANECDOTE

How Flat Replaced Flatten In JavaScript

  • The proposed array flatten method became 'flat' after compatibility concerns with MooTools prevented adding 'flatten'.
  • Will recounts the 'smoosh gate' debate and how legacy libraries forced a shorter name choice to avoid breaking sites.
INSIGHT

Symbols Let You Extend Without Breaking

  • Symbols let JavaScript and libraries add properties without colliding with existing names or surprising consumers.
  • Symbols are a metaprogramming primitive enabling hidden or opt-in behaviors while preserving old APIs.
ADVICE

Use Community Patterns As Proof Before Standardizing

  • Let userland libraries act as R&D: wait until patterns prove essential before standardizing them.
  • TC39 treats popular community patterns (e.g., Lodash usage) as a filtration system before adding to the language.
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