rewrite client in typescript

[SteffenDE]

This is similar to phoenixframework/phoenix_live_view#3789, but it goes one step further and actually changes all files to typescript.

Disclaimer: Claude translated most of the files, I did manual adjustments. This is work in progress.

[Copilot]

Pull Request Overview

This PR rewrites the JavaScript client into TypeScript, updates build and lint configurations, and adjusts tests accordingly.

• Converts all assets/js/phoenix sources to TypeScript and updates build output in priv/static
• Adds TypeScript support in package.json, ESLint, and Typedoc configs
• Updates test files for semicolons, imports, and TypeScript resolution

Reviewed Changes

Copilot reviewed 41 out of 49 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
typedoc.json	Added Typedoc configuration for new TS entry points
priv/static/phoenix.mjs	Regenerated client bundle refactored to use const/arrow and TS defaults
package.json	Added types, typescript, ts-jest, and new scripts for TS build
mix.exs	Updated assets.build alias to include TS compile step
eslint.config.mjs	Switched ESLint to use a TypeScript plugin and configs
assets/test/*.js/.ts	Updated tests with semicolons, import paths, and TS fixtures

Comments suppressed due to low confidence (4)

package.json:51

• There’s no build step before running tests, yet tests depend on the compiled TypeScript output. Consider adding a pretest script such as "pretest": "npm run build" to ensure sources are transpiled before Jest runs.

    "test": "jest",

typedoc.json:3

• [nitpick] Typedoc is pointing at the TS source. If you want to document the distributed API instead, consider pointing entryPoints at the compiled declaration file (e.g., assets/dist/phoenix/index.d.ts) to reflect the actual published API.

  "entryPoints": ["./assets/js/phoenix/index.ts"],

assets/test/socket_test.js:44

• Tests reference socket.longpollerTimeout, but the client property was renamed to longPollFallbackMs and no default of 20000 is set. Update the test to assert socket.longPollFallbackMs or add a backward‐compatible alias and default value.

      expect(socket.longpollerTimeout).toBe(20000);

eslint.config.mjs:4

• The ESLint config is importing from typescript-eslint, but the official plugin package is @typescript-eslint/eslint-plugin and you typically also need @typescript-eslint/parser. Update the import and parser settings accordingly.

import tseslint from "typescript-eslint";

[Copilot]

Default longPollFallbackMs is set to null instead of a meaningful default (e.g., 20000ms). Consider using opts.longPollFallbackMs ?? DEFAULT_LONG_POLL_FALLBACK_MS or exposing a longpollerTimeout alias for backward compatibility with existing tests.

Suggested change

	this.longPollFallbackMs = (_a = opts.longPollFallbackMs) !== null && _a !== void 0 ? _a : null;
	this.longPollFallbackMs = (_a = opts.longPollFallbackMs) ?? DEFAULT_LONG_POLL_FALLBACK_MS;