JSNES vs NESER

JSNES is a free JavaScript library for emulating NES games in browsers and Node.js. Its Browser helper handles canvas rendering, audio, keyboard and gamepad input, and frame timing; the lower-level NES class allows custom rendering and audio handling in Node.js. ROM data can be loaded from a URL or from a string, Uint8Array, or ArrayBuffer. The API runs frames, accepts controller input for either player, resets, adjusts frame rate, and includes methods for moving and triggering the Zapper. Applications can serialize and restore emulator state with `toJSON()` and `fromJSON()`. The `onBatteryRamWrite` callback lets an application capture battery-backed SRAM writes for persistent game saves. Sound emulation is enabled by default, with a default sample rate of 48000 Hz, and an audio callback is available. The README provides npm installation for Node.js or Webpack and an unpkg script for browser use, as well as a React embedding example. JSNES is licensed under Apache-2.0; its GitHub Issues tracker accepts bug reports and feature requests.

NESER is a free Nintendo emulation systems engine written in Rust, with desktop and browser frontends. It supports NES and Famicom variants, Game Boy and Game Boy Color, Game Boy Advance, and Super Nintendo systems. Shared platform code covers audio, video, input, save states, configuration, ROM browsing, and debugging. The native frontend supports keyboard and gamepad input, with NES-specific devices including the Zapper, SNES Mouse, Arkanoid paddle, Power Pad, and Four Score. NES users can choose shader presets such as CRT, NTSC, smooth, PAL, or none. The browser frontend accepts ROM files for the supported systems. For scripting and CI, headless mode runs a ROM and writes a PNG frame; the same ROM and frame count produce byte-identical captures across runs and builds. NES development tools include a debugger, CPU trace, breakpoints, and deterministic autorun recording and playback. A built-in open-source GBA BIOS means no external BIOS file is required. NESER is MIT-licensed and can be installed with cargo install neser or obtained as a prebuilt release.