bfirsh/jsnes

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A JavaScript NES emulator.

Stars: 6.4k
Forks: 857
Open beginner issues: 0
Indexed issues: 52

Dominant language: JavaScript
License: Apache-2.0
Last GitHub push: Jul 28, 2026
Latest indexed: Sep 14, 2026
Contributing guide: No contributing guide
Code of conduct: No code of conduct
Beginner labels: help wanted
PR merge metrics: No merged PRs in 30d

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52 open issues indexed

Jackal nes support Open

bfirsh/jsnes#44 · 5 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Why is the same value as 4 of the mapper appears to have some NES can be simulated and some can not be simulated? Open

bfirsh/jsnes#48 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Buttons commands not working for Zelda Open

bfirsh/jsnes#88 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Electron release Open

bfirsh/jsnes#91 · 1 comment · 11 reactions · 0 assignees · Indexed Sep 14, 2026
Gamepad web API integration Open

bfirsh/jsnes#108 · 3 comments · 2 reactions · 0 assignees · Indexed Sep 14, 2026
Add more code documentation Open

bfirsh/jsnes#110 · 0 comments · 8 reactions · 0 assignees · Indexed Sep 14, 2026
No way to save progress Open

bfirsh/jsnes#124 · 2 comments · 4 reactions · 0 assignees · Indexed Sep 14, 2026
Set up with semantic-release Open

bfirsh/jsnes#157 · 4 comments · 2 reactions · 0 assignees · Indexed Sep 14, 2026
BG color flashes. Open

bfirsh/jsnes#185 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
More Mappers? Open

bfirsh/jsnes#260 · 0 comments · 6 reactions · 0 assignees · Indexed Sep 14, 2026
Elite from the official elite website by Ian Bell Open

bfirsh/jsnes#273 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Feature idea: Implement WideNES for widescreen gameplay? Open

bfirsh/jsnes#300 · 2 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
[FEATURE REQUEST] Disk System Support Open

bfirsh/jsnes#307 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Jackal nes rom can't run. Open

bfirsh/jsnes#316 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Emulator hangs when playing my homebrew ROM Open

bug help wanted

bfirsh/jsnes#337 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Mapper5存在问题 Open

bfirsh/jsnes#353 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
How to change the speed? Open

bfirsh/jsnes#357 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Compatibility issues Open

bfirsh/jsnes#407 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Adapt for kaios Open

bfirsh/jsnes#409 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Mapper 30 support Open

bfirsh/jsnes#423 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
Mapper 30 using mapper 2 Open

bfirsh/jsnes#433 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
mapper4 There seems to be a problem Open

bfirsh/jsnes#437 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
When playing on a display that is higher than 60hz, games run faster than they are supposed to- leaving games nearly unplayable. Open

bfirsh/jsnes#445 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Super Mario Bros. (Two Players Hack) not working Open

bfirsh/jsnes#447 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Can you support these Roms? Open

bfirsh/jsnes#448 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Maximum call stack size exceeded Open

bfirsh/jsnes#460 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
add more mapper can you??? Open

bfirsh/jsnes#494 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Implement cycle-accurate DMA bus interleaving Open

bfirsh/jsnes#535 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Sprite issues in Punch-Out Open

bfirsh/jsnes#561 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Phone/tablet/touchscreen interface Open

bfirsh/jsnes#564 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Implement dot-level PPU rendering pipeline Open

bfirsh/jsnes#565 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Mapper coverage: status and roadmap Open

bfirsh/jsnes#568 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
AccuracyCoin: 32 remaining test failures Open

bfirsh/jsnes#591 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
ROM loader: header zeroing heuristic breaks NES 2.0 ROMs Open

bug component: rom difficulty: medium priority: high

bfirsh/jsnes#593 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
MMC3: IRQ counter has multiple correctness issues Open

accuracy bug component: mapper difficulty: hard priority: critical

bfirsh/jsnes#595 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
MMC5 (Mapper 5): completely non-functional stub Open

bug component: mapper difficulty: hard priority: high

bfirsh/jsnes#596 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
MMC1: multiple shift register and mirroring bugs Open

accuracy bug component: mapper difficulty: medium priority: medium

bfirsh/jsnes#598 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Add missing popular mappers (206, VRC, FME-7, MMC4) Open

component: mapper difficulty: hard enhancement priority: medium

bfirsh/jsnes#599 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Most mappers missing toJSON/fromJSON — save states lose bank state Open

bug component: mapper difficulty: medium priority: medium

bfirsh/jsnes#600 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
CPU: IRQ and reset interrupt handlers missing proper cycle timing Open

accuracy bug component: cpu difficulty: medium priority: medium

bfirsh/jsnes#602 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
CPU: CLI/SEI/PLP interrupt inhibit delay and BRK/NMI hijacking not implemented Open

accuracy component: cpu difficulty: hard enhancement priority: low

bfirsh/jsnes#603 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
PPU: no 8-sprite-per-scanline limit or sprite overflow flag Open

accuracy bug component: ppu difficulty: medium priority: high

bfirsh/jsnes#604 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
PPU: minor rendering issues (odd-frame skip, monochrome bg, sprite 0 left-column) Open

accuracy bug component: ppu difficulty: easy priority: low

bfirsh/jsnes#607 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
APU: various channel bugs (sequencer reset, length counter gating, timer stepping, noise LFSR) Open

accuracy bug component: apu difficulty: medium priority: medium

bfirsh/jsnes#609 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
TypeScript type definitions are incorrect Open

bug component: browser difficulty: easy priority: medium

bfirsh/jsnes#610 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Test coverage gaps: PPU, APU, controllers, mappers, browser, state serialization Open

difficulty: hard enhancement priority: medium

bfirsh/jsnes#617 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Fix sprite corruption in Castlevania III intro Open

bfirsh/jsnes#647 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
MMC1 (mapper 1): SUROM 512KB games crash — fixed bank at $C000 doesn’t follow the 256KB page-select bit Open

bfirsh/jsnes#732 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Tetris (NES) compatibility issues? (disappearing graphics) Open

bfirsh/jsnes#751 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Super Mario Bros. 3 and Kirby's Adventure sprite layer error and Audio issue Open

bfirsh/jsnes#771 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026

bfirsh/jsnes

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