"Subsequent variable declarations must have the same type"

Question

I am following this link to start a sample node js project using webworker-thread. https://www.npmjs.com/package/webworker-threads

here is my ts code:

var Worker = require('webworker-threads').Worker;
// var w = new Worker('worker.js'); // Standard API 

// You may also pass in a function: 
var worker = new Worker(function(){
  postMessage("I'm working before postMessage('ali').");
  this.onmessage = function(event) {
    postMessage('Hi ' + event.data);
    self.close();
  };
});
worker.onmessage = function(event) {
  console.log("Worker said : " + event.data);
};
worker.postMessage('ali');

i'm receiving this error:

C:\...\node_modules\ts-node\src\index.ts:300
        throw new TSError(formatDiagnostics(diagnosticList, cwd, ts, lineOffset))
              ^
TSError: ⨯ Unable to compile TypeScript
server.ts (1,5): Subsequent variable declarations must have the same type.  Variable 'Worker' must be of type '{ new (stringUrl: string): Worker; prototype: Worker; }', but here has type 'any'. (2403)
server.ts (5,25): Argument of type '() => void' is not assignable to parameter of type 'string'. (2345)
server.ts (6,3): Supplied parameters do not match any signature of call target. (2346)
server.ts (7,3): 'this' implicitly has type 'any' because it does not have a type annotation. (2683)
server.ts (7,29): Parameter 'event' implicitly has an 'any' type. (7006)
server.ts (8,5): Supplied parameters do not match any signature of call target. (2346)
server.ts (12,29): Parameter 'event' implicitly has an 'any' type. (7006)
    at getOutput (C:\...\node_modules\ts-node\src\index.ts:300:15)
    at C:\...\node_modules\ts-node\src\index.ts:330:16
    at Object.compile (C:\...\node_modules\ts-node\src\index.ts:489:17)
    at Module.m._compile (C:\...\node_modules\ts-node\src\index.ts:382:43)
    at Module._extensions..js (module.js:579:10)
    at Object.require.extensions.(anonymous function) [as .ts] (C:\...\node_modules\ts-node\src\index.ts:385:12)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Function.Module.runMain (module.js:604:10)

Answer 1

I do not guarantee this is so, but, as far as I see you are using the node import syntax. If you are compiling this using typescript than I may suggest using the typescript import syntax:

import {Worker} from 'webworker-threads'

or, in your typescript compiler configuration file set:

"allowJs":true

which might server to also enable the node syntax. Alternatively you could also do:

var Worker: any = <any>(require('webworker-threads').Worker);

and that would probably compile, but you will lose type information.