Open armandn opened 6 years ago
Unfortunately the base APIs for WebWorker and DOM are actually meaningfully different, and it's not clear at this point how to write a clean separation of global scopes between different parts of your project other than splitting your project into multiple parts.
We have found that what is meaningful in the global scope of a web worker is significantly more narrow than we find out of the DOM. So we tend to author with "lib": [ "dom" ]
and then just declare
the handful of APIs we require to make a web worker work, or we obtain a reference to the global object, treat it as any
, and pick off certain properties from the global scope and type them at the point where we pick them off.
While it isn't ideal, it saves us from the only other realistic option, splitting the code. If you have modular code, and pick off parts of a global scope and type them, and you are using modular code, you should be able to author isomorphic modules fairly easily. Here is an example of the most "bullet proof" way to get a reference to the global scope, which avoids any issues with CSP:
const globalObject: any = (function (): any {
if (typeof global !== 'undefined') {
// global spec defines a reference to the global object called 'global'
// https://github.com/tc39/proposal-global
// `global` is also defined in NodeJS
return global;
}
else if (typeof window !== 'undefined') {
// window is defined in browsers
return window;
}
else if (typeof self !== 'undefined') {
// self is defined in WebWorkers
return self;
}
})();
@kitsonk But, do I need to write your above code in every file? and use globalObject
for referring properties
How do I handle this scenario in here?
@shamhub , no, you would use the global object instead of self
import globalObject from 'globalObject'
globalObject.postMessage({});
That being said, in your case, you don't need the global object. If you want to get around the typing errors, you can just use
const ctx: Worker = self as any;
ctx.postMessage();
@charlesbodman I have used second option but I get error No webworker support
as mentioned here
@shamhub , it's because you're checking for worker support inside of the worker. No need.
@charlesbodman Yes it works now. In JS, we have SharedWorker
object. Am trying to execute the same code using let worker: SharedWorker = new SharedWorker('worker.js');
but I see the error Cannot find name 'SharedWorker'
SharedWorker needs to have its own lib file. mind filing a new ticket to track creating that.
logged https://github.com/Microsoft/TypeScript/issues/24323 to track adding SharedWorker
support
@mhegazy @DanielRosenwasser we're also running into the incompatible dom
and webworker
typings in Angular CLI projects and that leaves us in a tricky spot. I have described the situation in https://github.com/angular/angular-cli/pull/14188#discussion_r276566618.
I suppose the "right" approach would be for IDE support to better approximate compilation support by supporting multiple tsconfigs on the same folder that affect different combination of files. But that sounds hard and needs to be supported by the IDE proper as well.
I'm not sure what the correct approach is right now.
(Heads up, @mhegazy is no longer on the team. CCing @RyanCavanaugh)
We should reorganize this a bunch
lib.browser.d.ts
is things you can access from WW or DOM contextslib.window.d.ts
is just the definition of Window
lib.window.globals.d.ts
adds the existing arbitrarily-selected global values from Window
lib.webworkers.d.ts
is browser + ww-specific stufflib.dom.d.ts
is (for back compat) window + browser + window.globalsAny progress on this? I am having the same issue
There is a related problem that library developers (typings/d.ts
file providers) are facing. For libraries that actually work well in both the DOM and the webworker contexts, I don't see how it's possible to program against such a library in a webworker context, because whenever the library (only the d.ts file! not the source to be compiled!) contains a reference to a DOM type (like HTMLElement
), the compiler will bail out with a TS2304
, stating that the type cannot be found, even if the respective API is not used at all in the code to be compiled.
The only workaround I can see is to target "DOM" inside the webworker code (and declare all the webworker APIs that you need to use in order to make it compile) or to patch all the typings files and generate separate versions for use in webworkers, only. Although feasible, I don't like those workarounds. I would rather see the compiler be more lenient with respect to unused (with respect to the sources to are being compiled) declarations in a d.ts file.
To add to my previous comment above: For libraries, there actually is a work around: It's also an all-or-nothing flag, so really having more control over this would be appreciated: Use the skipLibCheck
option to disable checking of the .d.ts files that only compile cleanly in the "other" lib context.
Though it is a little bit ugly, here is a method I've gotten to work:
(self as unknown as Worker).postMessage(/* message */)
This actually makes the intellisense work on the postMessage
correctly as well in VSCode, by correctly forcing recognition of the type of self
. I dislike the as unknown
in the middle, but without that, I get a different TS error:
Conversion of type 'Window & typeof globalThis' to type 'Worker' may be a mistake because neither type sufficiently overlaps with the other. If this was intentional, convert the expression to 'unknown' first.
If there's a cleaner syntax for this, I'd love a hint. :)
@orta and I put our heads together on this to see if @RyanCavanaugh's proposed solution is workable. So far, we think Yes, with some caveats that we need to investigate. Here's are some notes; we'll work more on this soon.
lib.browser.d.ts
, would solve (a) and (b) -- just put the core things into browser and let webworker or dom respectively extend the core.browser
in an unsound way.this
parameter.onerror
and self
.self
is defined in the same way for both files, but webworker uses the much smaller type WorkerGlobalScope
instead of Window
. If it used the name Window
instead it would probably merge cleanly with the DOM's self
, although I haven't tested this yet.onerror
has a this
parameter for webworker, and doesn't allow strings as event names, nor does it have 4 trailing optional parameters. But it might be worthwhile to change it if it's the only conflict left.Having just discussed this on Gitter, I realized that the general problem here isn't just about dom
and webworker
, despite appearances; that's just a symptom. JS is ubiquitous nowadays and I'd expect it's not uncommon to have code for a few different platforms existing within the same source tree. But you only get one tsconfig.json
(for the purposes of IDE support and IntelliSense, at least), and lib
is global.
I actually have a similar problem to this today with miniSphere: the vast majority of a game will use the Sphere typings, but the build script--Cellscript.js
uses the Cell API, which like Web Workers vs. DOM, is generally distinct but shares a few select classes in common.
So if there were a way to use separate typings per-file or even just per-directory, that would be an elegant solution to this problem, I think, and probably wouldn't even require modifying the .d.ts
files as they're currently written.
In the meantime, the workaround I use is typing self
in the worker file:
/* eslint-env worker */
const worker: Worker = self as any;
worker.addEventListener("message", (e) => {
worker.postMessage({hello: "world"});
});
You can even go further and type the messages:
worker.ts
/* eslint-env worker */
type TRequest = {
myrequest: number;
};
type TResponse = {
myresponse: number;
};
export interface IRequestWorker {
postMessage: (message: TRequest) => void;
onmessage: (message: MessageEvent<TResponse>) => void;
}
interface IResponseWorker {
postMessage: (message: TResponse) => void;
onmessage: (message: MessageEvent<TRequest>) => void;
}
const worker: IResponseWorker = self as any;
// Receive from the main thread
worker.onmessage = ({data: {myrequest}}) => {
console.log(myrequest);
// Send to the main thread
worker.postMessage({myresponse: 222});
};
main.ts
/* eslint-env browser */
import type {IRequestWorker} from "./worker.ts";
const worker = new Worker(new URL("./worker.ts", import.meta.url)) as IRequestWorker;
// Receive from the worker
worker.onmessage = ({data: {myresponse}}) => {
console.log(myresponse);
};
// Send to the worker
worker.postMessage({myrequest: 111});
export {};
Having just discussed this on Gitter, I realized that the general problem here isn't just about
dom
andwebworker
, despite appearances; that's just a symptom. JS is ubiquitous nowadays and I'd expect it's not uncommon to have code for a few different platforms existing within the same source tree. But you only get onetsconfig.json
(for the purposes of IDE support and IntelliSense, at least), andlib
is global.I actually have a similar problem to this today with miniSphere: the vast majority of a game will use the Sphere typings, but the build script--
Cellscript.js
uses the Cell API, which like Web Workers vs. DOM, is generally distinct but shares a few select classes in common.So if there were a way to use separate typings per-file or even just per-directory, that would be an elegant solution to this problem, I think, and probably wouldn't even require modifying the
.d.ts
files as they're currently written.
This issue also manifests its self when using test frameworks that declare globals. It makes these globals available in each file even though they are not at runtime. It also means when you use multiple test frameworks that each declare globals of the same name, you get conflicting global definitions.
Having a mechanism for specifying different types for different file patterns sounds like a good solution to me.
As a stop-gap, it would be nice if there were a library called "DOMAndWebWorker" that was the intersection of the "DOM" and "WebWorker" libraries.
But to solve the problem in general, we can see from the fact that including "DOM" and "WebWorker" in compilerOptions.lib
results in an OR operation between the two libraries, that what we need is some way to do AND operations between libraries. Maybe the compilerOptions.lib
property could be set as a string, something like "ESNext | (DOM & WebWorker)".
So I guess I'm here after 6 years just wondering if there is some workaround cause all I would like is execute my classes and functions inside the webworker but in a typescript nice way. Is there a solution for that if I have e.g. a module and then want to import things from that module inside my worker?
All posts I saw seemed to be workarounds by waiting for webpack to compile it and then grab a specific module etc.
If one file need work on both dom and web worker, how to config the compilerOptions.lib?
For example:
if (typeof importScripts == 'function' && typeof window=='undefined') {
// some code for web worker
importScripts('abc.js');
} else {
// some code for dom
alert(document.title);
}
If one file need work on both dom and web worker, how to config the compilerOptions.lib?
The current state seems to be that there is no correct type-safe way to do this.
The only available option for module authors is to maintain two modules, one compiled for web worker and one compiled for DOM, and then a "dispatcher" module that imports both as un-typed javascript, uses a non-type-safe environment tester function to determine which one to call, and dispatches module consumer function calls to one or the other. That dispatcher module can then type itself, without referencing either "dom" or "webworker" definitions, and hide the kludge from consumers.
I got myself into a situation similar to #11093.
My project is designed to work either in the "main thread", with access to DOM, or as a WebWorker, where a different behavior kicks in. This was done for compatibility reasons and to have only one distributable js file and it's been working fine for the last two years.
In all this time I never specified the lib compiler option, only target ES5.
Today, as I'm experimenting some ES2015 stuff, I see that if I specify targets DOM,ES5,WebWorker,ES2015.Promise all hell breaks loose with errors. - Duplicate identifier, Subsequent variable declarations must have the same type.
Shouldn't this kind of mix be allowed in a project?