⚠️ Breaking Change
Impact Score: 7/10
Deno v1.4.0 — Release Notes & Engineering Impact
Source available — automated, not human-reviewed
Component: deno · Channel: stable. Automated analysis, not a compatibility certification. How this works.
Analysis updated: 2026-11-01.
Breaking-change evidence from the source
- BREAKING(std/fs): remove writeJson and writeJsonSync (#7256)
- BREAKING(std/fs): remove readJson and readJsonSync (#7255)
- BREAKING(std/ws): remove connect method (#7403)
⚡ Executive Summary (TL;DR)
Deno v1.4.0. Source highlight: feat: Implement WebSocket API (#7051, #7437)
Who Does This Impact? (Role-Based Analysis)
💻 Software Engineers & Devs
Check the source notes against the package and APIs you use before upgrading.
📊 Product & Engineering Leads
Use the documented changes to assess relevance to your product; release frequency alone is not a quality measure.
⚙️ DevOps & Security
Verify the target version, runtime requirements and rollback procedure in the official documentation.
⚠️ Breaking Changes & Deprecations (3)
- - BREAKING(std/fs): remove writeJson and writeJsonSync (#7256)
- - BREAKING(std/fs): remove readJson and readJsonSync (#7255)
- - BREAKING(std/ws): remove connect method (#7403)
✨ New Features & Capabilities (6)
- feat: Implement WebSocket API (#7051, #7437)
- feat(console): print proxy details (#7139)
- feat(console): support CSS styling with "%c" (#7357)
- feat(core): Add JSON ops (#7336)
- feat(fmt, lint): show number of checked files (#7312)
- feat(info): Dependency count and sizes (#6786, #7439)
⚡ Performance & Enhancements (2)
- refactor: Improve placeholder module names (#7430)
- refactor: improve tsc diagnostics (#7420)
🔧 Bug Fixes & Patches (6)
- fix: Empty Response body returns 0-byte array (#7387)
- fix: panic on process.kill() after run (#7405)
- fix: colors mismatch (#7367)
- fix: compiler config resolution using relative paths (#7392)
- fix(core): panic on big string allocation (#7395)
- fix(op_crates/web): Use "deno:" URLs for internal script specifiers (#7383)
📄 View Raw Release Notes (Original Developer Log)
### 1.4.0 / 2020.09.13
- feat: Implement WebSocket API (#7051, #7437)
- feat(console): print proxy details (#7139)
- feat(console): support CSS styling with "%c" (#7357)
- feat(core): Add JSON ops (#7336)
- feat(fmt, lint): show number of checked files (#7312)
- feat(info): Dependency count and sizes (#6786, #7439)
- feat(install): bundle before installation (#5276)
- feat(op_crates/web): Add all single byte encodings to TextDecoder (#6178)
- feat(unstable): Add Deno.systemMemoryInfo() (#7350)
- feat(unstable): deno run --watch (#7382)
- feat(unstable): deno test --coverage (#6901)
- feat(unstable): enable importsNotUsedAsValues by default (#7413)
- feat(unstable): enable isolatedModules by default (#7327)
- fix: Empty Response body returns 0-byte array (#7387)
- fix: panic on process.kill() after run (#7405)
- fix: colors mismatch (#7367)
- fix: compiler config resolution using relative paths (#7392)
- fix(core): panic on big string allocation (#7395)
- fix(op_crates/web): Use "deno:" URLs for internal script specifiers (#7383)
- refactor: Improve placeholder module names (#7430)
- refactor: improve tsc diagnostics (#7420)
- refactor(core): merge CoreIsolate and EsIsolate into JsRuntime (#7370, #7373,
#7415)
- refactor(core): Use gotham-like state for ops (#7385)
- upgrade: deno_doc, deno_lint, dprint, swc (#7381, #7391, #7402, #7434)
- upgrade: rusty_v8 0.10.0 / V8 8.7.75 (#7429)
Changes in std version 0.69.0:
- BREAKING(std/fs): remove writeJson and writeJsonSync (#7256)
- BREAKING(std/fs): remove readJson and readJsonSync (#7255)
- BREAKING(std/ws): remove connect method (#7403)