JavaScriptCore
Hacker ApprovedShares rank 4 of 7 JavaScript engines by recommenders
Apple's JavaScript engine, used by WebKit and Bun, with well-tuned JIT performance and a long track record on consumer devices.
Apple's JavaScript engine, used by WebKit and Bun, with well-tuned JIT performance and a long track record on consumer devices.
19 people gave an opinion
- recommend it
- 14
- criticize it
- 5
- approval share
- 74%
Recommended in 9 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: not recommended
- March 2026: recommended
- April 2026: not recommended
- May 2026: recommended
- June 2026: recommended
- July 2026: recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: not recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 14 people recommend itNeeds 10 or more, met.
- 2.8 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 9 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Well-tuned, fast JIT performance
“v8 and JSC also have decades of performance tuning across basically every consumer device.”
Comment from 13 Aug 2026 in “DeepSeek Harness” “JSC is more optimized for memory and is faster to tier up early/less overhead”
Comment from 11 Mar 2026 in “Zig – Type Resolution Redesign and Language Changes” “I didn't know JavaScriptCore consistently outperformed V8”
Comment from 4 Jan 2026 in “JavaScript engines zoo – Compare every JavaScript engine” - Comment from 2 Nov 2025 in “Notes by djb on using Fil-C”
- Comment from 25 Jan 2026 in “I'm posting this from a memory safe web browser”
Proven in WebKit, iOS and macOS
“It's used by WebKit, so it works really well and is very unlikely to disappear.”
Comment from 15 Mar 2026 in “Hammerspoon” “it is certainly used in plenty of "real-world tasks" daily in iOS and macOS”
Comment from 2 Dec 2025 in “Anthropic acquires Bun” “until WebKit/JavaScriptCore shipped PTC and literally no one bat an eye”
Comment from 4 Jan 2026 in “JavaScript engines zoo – Compare every JavaScript engine” Default choice for embedding JavaScript
“Reaching for an existing Javascript interpreter such as JavaScriptCore or V8 is the logical choice.”
Comment from 26 May 2026 in “Native all the way, until you need text” “followed closely by JavaScriptCore which is what Bun uses”
Comment from 2 Dec 2025 in “Anthropic acquires Bun” Good at restricting JavaScript execution
“restricts JS in all of the ways I wished I could restrict the language back when I was working on JSC”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “JavaScriptCore is super friendly to pointer capabilities”
Comment from 5 Sep 2026 in “Actively exploited sandbox RCE in all Chromium versions”
Other JavaScript engines people recommend
The four most recommended other JavaScript engines, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Criticize | Approval | Months | Owned | Badge |
|---|---|---|---|---|---|---|
| V8 JavaScript engine | 59 | 36 | 62% | 12 | — | — |
| QuickJS | 33 | 8 | 80% | 10 | — | Approved |
| MicroQuickJS | 19 | 8 | 70% | 3 | — | — |
| JavaScriptCoreThis page | 14 | 5 | 74% | 9 | — | Approved |
| Boa JavaScript engine | 14 | 7 | 67% | 3 | — | — |
What people said
21 of the 23 comments that mention it, newest first. Each links to the original comment.
“JavaScriptCore is super friendly to pointer capabilities”
“v8 and JSC also have decades of performance tuning across basically every consumer device.”
“we are going to continue using C & C++ libraries like JavaScriptCore so it will always have more unsafe than pure Rust projects”
“it goes far beyond “piping the input””
“So your blame should be directed to Apple.”
“AIs hallucinating a multithreaded JSC is not boring, it's scary.”
“Evidently based on prior art by Mr. Pizlo”
“Reaching for an existing Javascript interpreter such as JavaScriptCore or V8 is the logical choice.”
“JavaScriptCore does have some different runtime characteristics and it is nice”
“the main source of problem was the engine, not their Zig code”
“V8 and JSC totally crapped out”
“It's used by WebKit, so it works really well and is very unlikely to disappear.”
“JSC is more optimized for memory and is faster to tier up early/less overhead”
“JSC's JITs are dear to my heart”
“until WebKit/JavaScriptCore shipped PTC and literally no one bat an eye”
“I didn't know JavaScriptCore consistently outperformed V8”
“restricts JS in all of the ways I wished I could restrict the language back when I was working on JSC”
“followed closely by JavaScriptCore which is what Bun uses”
“it is certainly used in plenty of "real-world tasks" daily in iOS and macOS”
“V8/JSC/SM, but they don't exactly fit with the "lightweight ethos"”
“have pretty decent JITs nowadays”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.