Firenvim: How It Works and Why It Sucks

Who am I?

• glacambre
• Neovim
• Tridactyl: Modal internet browsing
• Ileum, Syncwd, Shelley: ZSH integrations
• Nwin: Neovim GUI for Sway/i3
• Firenvim: Integrating Neovim in Chrome, Firefox, Thunderbird, Qutebrowser...

What's Firenvim?

Neovim GUIs, how do they work?

Libnvim:

Direct function calls

Performance

Access to neovim internals

RPC:

MessagePack

More documented

Easier to get started

Different contexts

• Reading from textarea:

  
  						let content = document.activeElement.textContent;
  					

• Reading from CodeMirror:

  
  					export function executeInPage(code: string): Promise<any> {
  							return new Promise((resolve, reject) => {
  									const script = document.createElement("script");
  									const eventId = (new URL(browser.runtime.getURL(""))).hostname + Math.random();
  									script.innerHTML = `(async (evId) => {
  											try {
  													let result;
  													result = await ${code};
  													window.dispatchEvent(new CustomEvent(evId, {
  															detail: {
  																	success: true,
  																	result,
  															}
  													}));
  											} catch (e) {
  													window.dispatchEvent(new CustomEvent(evId, {
  															detail: { success: false, reason: e },
  													}));
  											}
  									})(${JSON.stringify(eventId)})`;
  									window.addEventListener(eventId, ({ detail }: any) => {
  											script.parentNode.removeChild(script);
  											if (detail.success) {
  													return resolve(detail.result);
  											}
  											return reject(detail.reason);
  									}, { once: true });
  									document.head.appendChild(script);
  							});
  					}
  					executeInPage(`(()=>{return document.getElementById(Id).CodeMirror.getValue()})`);
  					

• Firefox:
  • Patched Firefox: not viable, requires recompiling
  • Obscure APIs (wrappedJSObject) not part of WebExtension standard
• Chrome
  • No solution. Especially with newer webextension standard...

• Keyboard shortcut events are mangled (OSX)
• Some keyboard shortcuts (e.g.

  <C-w>

  are reserved). Workarounds:
  • Chrome: Use separate webextension API for reserved shortcuts
  • Firefox: Hotpatch firefox (thanks @alerque!)

• Webextension API requires manifest/registry to exist
• Can't choose args used to run neovim
• Can't choose protocol to communicate with neovim

Thanks for listening!