JSFiddle - React, Tailwind, and code Playground

JavaScript

var proxy=new Proxy({},{
            get(target,key) {
                if (key=='a') return 'A';
                if (key=='b') return 'B';
                if (key=='c') return 'C';
                if (key=='then') return 'THEN!';
            }
});
        
async test() {
	alert(proxy.a);
	alert(proxy.b);

	//alert(await proxy);
}

test();