Trying to call a method within a closure without binding the initial context can lead to change the value of "this"

closure_class_method_bindings.js

//////////////////////// NOT WORKING: CASE 1 ////////////////////////

class ClosureMethodWithoutBind{

    constructor(prop){
        this.prop = prop;
    }

    changeAfter(cb, milis){
        setTimeout(cb,milis);
    }

    emptyProp(){
        this.prop = '';
    }

    emptyPropAfter(milis){
        this.changeAfter(this.emptyProp, milis);
    }

    log(){
        console.log('prop: %s', this.prop);
    }

}

var c1 = new ClosureMethodWithoutBind('Angel');
c1.log();
// console -> prop: Angel
c1.emptyPropAfter(100);
setTimeout(() => c1.log(), 200);
// console -> prop: Angel


//////////////////////// WORKING: CASE 2 ////////////////////////

class ClosureMethodWithBind{

    constructor(prop){
        this.prop = prop;
        this.emptyProp = this.emptyProp.bind(this);
    }

    changeAfter(cb, milis){
        setTimeout(cb,milis);
    }

    emptyProp(){
        this.prop = '';
    }

    emptyPropAfter(milis){
        this.changeAfter(this.emptyProp, milis);
    }

    log(){
        console.log('prop: %s', this.prop);
    }

}

var c2 = new ClosureMethodWithBind('Angel');
c2.log();
// console -> prop: Angel
c2.emptyPropAfter(100);
setTimeout(() => c2.log(), 200);
// console -> prop: 


//////////////////////// WORKING: CASE 3 ////////////////////////

class ClosureMethodWithImplicitBind{

    constructor(prop){
        this.prop = prop;
    }

    changeAfter(cb, milis){
        setTimeout(cb,milis);
    }

    emptyProp = () => (this.prop = '');

    emptyPropAfter(milis){
        this.changeAfter(this.emptyProp, milis);
    }

    log(){
        console.log('prop: %s', this.prop);
    }

}

var c3 = new ClosureMethodWithImplicitBind('Angel');
c3.log();
// console -> prop: Angel
c3.emptyPropAfter(100);
setTimeout(() => c3.log(), 200);
// console -> prop: