JSFiddle - React, Tailwind, and code Playground

JavaScript

var Test = function () {
        console.log("constructor");
        this.positions = [];
        console.log(this.positions);
        console.log("constructorEnd");
        this.addPosition = function () {
            console.log(this.positions);
            var i = this.positions.length;
            this.positions[i] = "aa";
            console.log(this.positions);
        }
    }
    var t = new Test();
    console.log("constructed");
    t.addPosition();