SOURCE

class A {
    constructor(name) {
        this.name = name
    }
    toString() {
        console.log("this is father A", this.name)
    }
}

class Ac extends A {
    constructor(name) {
        super(name)
        this.name = name + 'child'
    }
    
    toString() {
        super.toString()
        console.log("this is child Ac")
    }
}

const a = new Ac('test')
a.toString()