The Liar paradox is not so paradoxical if seen as an automata.

liar.js

class Automata {
    constructor() {
        this.sentence = false;
    }

    run() {
        while (true) {
            console.log(`This sentence is ${this.sentence}.`);
            if (this.sentence === false) {
                this.sentence = true;
            } else if (this.sentence === true) {
                this.sentence = false;
            }
        }
    }
}

(function main() {    
    const automata = new Automata();
    automata.run();
})();