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2025.11.16 | JSConf JP 2025 | @progfay
`Error.prototype.stack`:
Present & Future
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ɾWeb Frontend Engineer
ɾI like...
ɾ🔍 Researching Web Trends
ɾ🎤 Japanese Rap
Name: Shunsuke Mano @progfay
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No content
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Error.prototype.stack - JavaScript | MDN
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Let's deep dive into Error.prototype.stack !
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V8
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V8 v8/src/execution/messages.cc at 5ac61190087feaa7fda2284f9f06e227141444ee · v8/v8
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V8 - Stack trace API Stack trace API · V8
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Node.js node/lib/internal/errors.js at 622c3721bf61e0bda825bed821e316e19ba75eff · nodejs/node
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Node.js
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Deno
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JSC
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JSC WebKit/Source/JavaScriptCore/interpreter/Interpreter.cpp at 66754d9a9c19aa6402c09970adc0191c460980cc · WebKit/WebKit
WebKit/Source/JavaScriptCore/runtime/StackFrame.cpp at 66754d9a9c19aa6402c09970adc0191c460980cc · WebKit/WebKit
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JSC
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Bun
🤯
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Bun bun/src/bun.js/bindings/FormatStackTraceForJS.cpp at 0db90b25261d4379103a4574e722362ed52a31cc · oven-sh/bun
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https://x.com/bunjavascript/status/1966814439744958941
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SpiderMonkey
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SpiderMonkey
JS::BuildStackString (SavedStacks.cpp - mozsearch) - 45e3c8634099e0f57fa0e7660dba85580a5dd8e7
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SpiderMonkey
JS::FormatSpiderMonkeyStackFrame (SavedStacks.cpp - mozsearch) - 45e3c8634099e0f57fa0e7660dba85580a5dd8e7
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SpiderMonkey
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So many runtimes, so many stack formats...
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It's time to standardize!
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tc39/proposal-error-stacks - GitHub
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proposal-error-stacks
• ECMAScript Proposal, specs, and reference implementation
for Error.prototype.stack / System.getStack / System.getStackString
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proposal-error-stacks
• ECMAScript Proposal, specs, and reference implementation
for Error.prototype.stack / System.getStack / System.getStackString
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I believe is this seems like too much, too big,
not well motivated as a big proposal.
Make we could split it up.
やりすぎ、
大
きすぎ、根拠も不
十
分に
見
える。
分割しよう。
notes/meetings/2024-12/december-05.md at 3bb70e4b6745798dc145be6859c92a7a0b6d0100 · tc39/notes
proposal-error-stacks
EN
JP
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• getter: calc & cache formatted stack
• setter: update cache
V8's Error.prototype.stack is exotic!
v8/src/execution/messages.cc at 740213e7e48558f16b6842bb74be0086ac2980d2 · v8/v8 v8/src/builtins/accessors.cc at 740213e7e48558f16b6842bb74be0086ac2980d2 · v8/v8
check cache & return if exists
set cache
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tc39/proposal-error-stack-accessor - GitHub
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proposal-error-stack-accessor
• focus Error.prototype.stack accessor (getter / setter)
• the only requirement is that it return a string
Spec - Error Stack Accessor
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Conclusion
• Present: So many runtime, so many stack format
• Standardizing activity: proposal-error-stacks, proposal-error-stack-accessor
• Future: runtimes may provide Structured stack frame
There's long way to go...