Encapsulation using class in Javascript

Question

After looking at some examples of encapsulation using Javascript, most of the examples create the object like:

function f (parameter) {
  var private = 1;
}

Would it be possible/good practice to create an object using class, similarly to Java like:

class f {
  var x;
  constructor(parameter) {
    x = parameter;
  }
  getX() {
    return x;
  }
}