Why is the class return empty prototype object first time in javascript?

Question

I have a code in below, as you see when console.log the prototype of the class first time, it return empty, but the object new from this class actually can response those method

Answer 1

how can explain it?

Methods/properties created through the class syntax are non-enumerable and it seems that the environment you log the value in doesn't show non-enumerable properties. console.log is not standardized, so different outputs in different environments have to be expected.

Creating a property through assignment always creates an enumerable property.

class Polygon {
  constructor(height, width) {
    this.height = height;
    this.width = width;
  }

  get area() {
    return this.calcArea()
  }

  calcArea() {
    return this.height * this.width;
  }
}
Polygon.prototype.test = function(){ return "test"}

// Note the different values for `enumerable`
console.log(Object.getOwnPropertyDescriptor(Polygon.prototype, 'calcArea'));
console.log(Object.getOwnPropertyDescriptor(Polygon.prototype, 'test'));