const ctx: Worker = self as any;
ctx.addEventListener('message', (e) => {
    // console.log(e)
    if (e.data === 'do some work') {
        console.log('Worker is about to start some work');
        let count: number = 0;
        for (let i: number = 0; i < 1000; i++) {
            count += i;
        }
        ctx.postMessage({ message: count });
    }
})

let worker: Worker = new Worker('worker.js');
worker.postMessage('do some work');

{

    "compilerOptions": {

      "lib": ["es2015", "dom"]
    },
    "files": [
      "./1_webworker/tstut.ts",
      "./1_webworker/worker.ts"

    ]
  }