RunFunctionInWebWorker.js

function runWebWorker(func) {
  if (typeof func !== "function") {
    throw new Error("Argument must be a function");
  }
  if (func.name === "") {
    throw new Error("Function must have a valid name");
  }
  return function (args) {
    return new Promise((resolve, reject) => {
      const code = `
       self.addEventListener('message',  function (e) {
      			const {funcCode, args} = e.data;
            const code ="function func(args) { return (" +  funcCode + ")(args)} " 
            eval(code);
            func(args)
            .then(self.postMessage)
            .catch(self.postMessage)
      }, false);     
      `;

      const blob = new Blob([code], {type: 'text/javascript'});
      const url = window.URL.createObjectURL(blob);
      const worker = new Worker(url);

      worker.postMessage({
        funcCode: func.toString(),
        args
      })

      worker.addEventListener('message', (e) => {
        resolve(e.data)
        window.URL.revokeObjectURL(url);
        worker.terminate();
      }, false);


    });
  }
}


function upperCase(str) {
  return new Promise((resolve, reject) => {
    resolve(str.toUpperCase())
  })
}

const upperCaseInWebWorker = runWebWorker(upperCase)

upperCaseInWebWorker("word")
  .then((e) => alert("Result from webworker: " +  e))
  .catch((e) => alert("Error", e))