Typescript: TS2496: The 'arguments' object cannot be referenced in an arrow function in ES3 and ES5. Consider using a standard function expression

Question

I followed some tutorials like http://www.html5rocks.com/en/tutorials/frameworks/angular-websockets/ to implement socket.io in my node.js server and angular.js client, everything works fine.

However, client side, Typescript display following compilation error:

TS2496: The 'arguments' object cannot be referenced in an arrow function in ES3 and ES5. Consider using a standard function expression.

Regarding following service codes:

on(eventName:string, callback) {
  this.socket.on(eventName, () => {
    var args = arguments; // <-- here the compilation error
    this.$rootScope.$apply(() => {
      callback.apply(this.socket, args);
    });
  });
}

emit(eventName:string, data, callback?) {
  this.socket.emit(eventName, data, () => {
    var args = arguments; // <-- here the compilation error
    this.$rootScope.$apply(() => {
      if (callback) {
        callback.apply(this.socket, args);
      }
    });
  });
}

I tried different solutions, like the one described in the first post of https://github.com/Microsoft/TypeScript/issues/1609, which fix the compilation but break the socket.io "on" functionality (the json objects aren't interpreted anymore).

Any idea how to fix or ignore this typescript compilation error?

Answer 1

Another possibility is to use a rest parameter instead of arguments:

on(eventName:string, callback) {
  this.socket.on(eventName, (...args) => {
    this.$rootScope.$apply(() => {
      callback.apply(this.socket, args);
    });
  });
}