@val-town/codemirror-ts v1.0.0-alpha.0

codemirror-ts

TypeScript extensions for CodeMirror. This aims to support as much of the basic interactions with TypeScript code as possible in CodeMirror.

Currently provides

• Hover hints for types
• Autocomplete
• Diagnostics (lints, in CodeMirror's terminology)

Peer dependencies

This module does not depend on anything: your project should have direct dependencies to:

• @codemirror/view
• @codemirror/lint
• @codemirror/autocomplete

Using these extensions

This is designed to scale up to more complex scenarios, so there is some assembly required. We could encapsulate more, but that would mean removing important points of control.

1. Create a TypeScript environment.

We don't create a TypeScript environment for you. This you bring, and it probably is used for other parts of your application. The simplest setup would be something like this, using @typescript/vfs:

import {
  createDefaultMapFromCDN,
  createSystem,
  createVirtualTypeScriptEnvironment,
} from "@typescript/vfs";

const fsMap = await createDefaultMapFromCDN(
  { target: ts.ScriptTarget.ES2022 },
  "3.7.3",
  true,
  ts,
);
const system = createSystem(fsMap);
const compilerOpts = {};
const env = createVirtualTypeScriptEnvironment(system, [], ts, compilerOpts);

2. Install the sync extension:

This extension powers the rest: when you make changes in your editor, this mirrors them to the TypeScript environment using createFile and updateFile in the TypeScript compiler.

Note, also, that we're supplying a path. These extensions use file paths in order to differentiate between different editor instances and to allow editors to import & export to & from one another. So each extension has a required path parameter, as well as the env parameter which should be your TypeScript environment.

import { tsSync } from "@valtown/codemirror-ts";

let env = "index.ts";

let editor = new EditorView({
  extensions: [
    basicSetup,
    javascript({
      typescript: true,
      jsx: true,
    }),
    tsSync({ env, path }),
  ],
  parent: document.querySelector("#editor"),
});

Linting

The tsLinter extension can be initialized like this and added to the extensions array in the setup of your CodeMirror instance.

tsLinter({ env, path });

This uses the @codemirror/lint package and grabs diagnostics from the TypeScript environment.

If you want to modify how lints are handled, you can use the getLints({ env, path }) method and wire it up with CodeMirror's linter method yourself.

Autocompletion

To make it possible to combine different autocompletion sources, we expose a CompletionSource((https://codemirror.net/docs/ref/#autocomplete.autocompletion) which you can use with the CodeMirror autocomplete method:

autocompletion({
  override: [tsAutocomplete({ env, path })],
});

We expose a lower-level interface to autocompletions with the getAutocompletion({ env, path, context }) method that takes a CompletionContext parameter.

Hover

The hover definition can be used like the following:

tsHover({
  env,
  path,
});

Which automatically uses a default renderer. However, you can customize this to your heart's content, and use your web framework to render custom UI if you want to, using the renderTooltip option.

tsHover({
  env,
  path,
  renderTooltip: (info: HoverInfo) => {
    const div = document.createElement("div");
    if (info.quickInfo?.displayParts) {
      for (let part of info.quickInfo.displayParts) {
        const span = div.appendChild(document.createElement("span"));
        span.className = `quick-info-${part.kind}`;
        span.innerText = part.text;
      }
    }
    return { dom: div };
  },
});

Roadmap

• Support for a TypeScript environment in a WebWorker