[рони]

slark,

class btn {
            constructor(className) {
                this.className = className;
                this.btn = document.querySelector(className);
                this.btn.addEventListener('click', this.btnClick.bind(this));
                this.btnClick()
            }

            btnClick() {
                console.log('Привет: ' + this.className)
            }
        }

        let btn1 = new btn('.btn-1')

        let btn2 = new btn('.btn-2')