JSFiddle - React, Tailwind, and code Playground

JavaScript

class MyClass {
  constructor() {
  	this.points = [];
  	this.setupMyClass();
  }
  
  setupMyClass() {
    let {points} = this;
    points = [...points, {x: 20, y:20}];
    
    // ugly code
    //this.points = [...this.points, {x: 20, y: 20}];
    
    console.log('points', points);
    console.log('this.points', this.points);
  }
}

myClassInstance = new MyClass();