Convert ActionCable javascript to ES2015 modules with a modern build environment #34177

- Rename action_cable/*.coffee -> *.js - Move app/assets/javascripts/* -> app/javascript/* - Rename action_cable.js.erb -> action_cable/index.js.erb Renaming the extension to .js is in preparation for converting these files from coffeescript to ES2015. Moving the files to app/javascript and putting the entry point in index.js.erb changes the structure of ActionCable's javascript to match the structure of ActiveStorage's javascript. (We are doing the file moving and renaming in a separate commit to ensure that the git history of the files will be preserved - i.e. git will track these as file renames rather than unrelated file additions/deletions. In particular, git blame will still trace back to the original authorship.)

Using [decaffeinate], we have converted these files from coffeescript syntax to ES2015 syntax. Decaffeinate is very conservative in the conversion process to ensure exact coffeescript semantics are preserved. Most of the time, it's safe to clean up the code, and decaffeinate has left suggestions regarding potential cleanups we can take. I'll tackle those cleanups separately. After running decaffeinate, I ran: ``` eslint --fix app/javascript ``` using the eslint configuration from ActiveStorage to automatically correct lint violations in the decaffeinated output. This removed 189 extra semicolons and changed one instance of single quotes to double quotes. Note: decaffeinate and eslint can't parse ERB syntax. So I worked around that by temporarily quoting the ERB: ```diff @ActionCable = - INTERNAL: <%= ActionCable::INTERNAL.to_json %> + INTERNAL: "<%= ActionCable::INTERNAL.to_json %>" WebSocket: window.WebSocket logger: window.console ``` and then removing those quotes after running decaffeinate and eslint. [decaffeinate]: https://github.com/decaffeinate/decaffeinate

- Remove unnecessary Array.from usages from subscriptions.js These were all Arrays before, so Array.from is a no-op - Remove unnecessary IIFEs from subscriptions.js - Manually decaffeinate sample ActionCable code in comments Here the coffeescript -> ES2015 conversion was done by hand rather than using decaffeinate, because these code samples were simple enough. - Refactor ActionCable.Subscription to avoid initClass - Refactor ActionCable.Subscription to use ES2015 default parameters - Refactor ActionCable.ConnectionMonitor to avoid initClass - Refactor ActionCable.ConnectionMonitor to use shorter variations of null checks - Remove unnecessary code created because of implicit returns in ConnectionMonitor This removes the `return` statements that were returning the value of console.log and those from private methods whose return value was not being used. - Refactor ActionCable.Connection to avoid initClass - Refactor Connection#isProtocolSupported and #isState This addresses these three decaffeinate cleanup suggestions: - DS101: Remove unnecessary use of Array.from - DS104: Avoid inline assignments - DS204: Change includes calls to have a more natural evaluation order It also removes the use of Array.prototype.includes, which means we don't have to worry about providing a polyfill or requiring that end users provide one. - Refactor ActionCable.Connection to use ES2015 default parameters - Refactor ActionCable.Connection to use shorter variations of null checks - Remove return statements that return the value of console.log() in ActionCable.Connection - Simplify complex destructure assignment in connection.js decaffeinate had inserted ``` adjustedLength = Math.max(protocols.length, 1) ``` to be safe, but we know that there has to always be at least one protocol, so we don't have to worry about protocols.length being 0 here. - Refactor Connection#getState The decaffeinate translation of this method was not very clear, so we've rewritten it to be more natural. - Simplify destructure assignment in connection.js - Remove unnecessary use of Array.from from action_cable.js.erb - Refactor ActionCable#createConsumer and #getConfig This addresses these two decaffeinate cleanup suggestions: - DS104: Avoid inline assignments - DS207: Consider shorter variations of null checks - Remove unnecessary code created because of implicit returns in action_cable.js.erb This removes the `return` statements that were returning the value of console.log and those from methods that just set and unset the `debugging` flag. - Remove decaffeinate suggestion about avoiding top-level this In this case, the top-level `this` is intentional, so it's okay to ignore this suggestion. - Remove decaffeinate suggestions about removing unnecessary returns I did remove some of the return statements in previous commits, where it seemed appropriate. However, the rest of these should probably remain because the return values have been exposed through the public API. If we want to break that contract, we can do so, but I think it should be done deliberately as part of a breaking-API change (separate from this coffeescript -> ES2015 conversion) - Remove unused `unsupportedProtocol` variable from connection.js Leaving this would cause eslint to fail - Refactor Subscriptions methods to avoid `for` ... `of` syntax Babel transpiles `for` ... `of` syntax to use `Symbol.iterator`, which would require a polyfill in applications that support older browsers. The `for` ... `of` syntax was produced by running `decaffeinate`, but in these instances a simpler `map` should be sufficient and avoid any `Symbol` issues.

…vironment We've replaced the sprockets `//= require` directives with ES2015 imports. As a result, the ActionCable javascript can now be compiled with rollup (like ActiveStorage already is). - Rename action_cable/index.js.erb -> action_cable/index.js - Add rake task to generate a javascript module of the ActionCable::INTERNAL ruby hash This will allow us to get rid of ERB from the actioncable javascript, since it is only used to interpolate ActionCable::INTERNAL.to_json. - Import INTERNAL directly in ActionCable Connection module This is necessary to remove a load-order dependency conflict in the rollup-compiled build. Using ActionCable.INTERNAL would result in a runtime error: ``` TypeError: Cannot read property 'INTERNAL' of undefined ``` because ActionCable.INTERNAL is not set before the Connection module is executed. All other ActionCable.* references are executed inside of the body of a function, so there is no load-order dependency there. - Add eslint and eslint-plugin-import devDependencies to actioncable These will be used to add a linting setup to actioncable like the one in activestorage. - Add .eslintrc to actioncable This lint configuration was copied from activestorage - Add lint script to actioncable This is the same as the lint script in activestorage - Add babel-core, babel-plugin-external-helpers, and babel-preset-env devDependencies to actioncable These will be used to add ES2015 transpilation support to actioncable like we have in activestorage. - Add .babelrc to actioncable This configuration was copied from activestorage - Enable loose mode in ActionCable's babel config This generates a smaller bundle when compiled - Add rollup devDependencies to actioncable These will be used to add a modern build pipeline to actioncable like the one in activestorage. - Add rollup config to actioncable This is essentially the same as the rollup config from activestorage - Add prebuild and build scripts to actioncable package These scripts were copied from activestorage - Invoke code generation task as part of actioncable's prebuild script This will guarantee that the action_cable/internal.js module is available at build time (which is important, because two other modules now depend on it). - Update actioncable package to reference the rollup-compiled files Now that we have a fully functional rollup pipeline in actioncable, we can use the compiled output in our npm package. - Remove build section from ActionCable blade config Now that rollup is responsible for building ActionCable, we can remove that responsibility from Blade. - Remove assets:compile and assets:verify tasks from ActionCable Now that we've added a compiled ActionCable bundle to version control, we don't need to compile and verify it at publish-time. (We're following the pattern set in ActiveStorage.) - Include compiled ActionCable javascript bundle in published gem This is necessary to maintain support for depending on the ActionCable javascript through the Sprockets asset pipeline. - Add compiled ActionCable bundle to version control This mirrors what we do in ActiveStorage, and allows ActionCable to continue to be consumed via the sprockets-based asset pipeline when using a git source instead of a published version of the gem.

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Convert ActionCable javascript to ES2015 modules with a modern build environment #34177

Convert ActionCable javascript to ES2015 modules with a modern build environment #34177

Commits on Nov 2, 2018