js class to wrap setinterval and make a start/stopable thunk with ~private state

repeated.js

class Repeated {

    constructor(delay, cond, fn, state) {
	this.delay = delay;
	this.cond = cond;
	this.fn = fn;
	this.state = state;
	this.timer = null;
	this.timers = [];
    }

    fun() {
	return () => {
	    console.log('fun');
	    if (this.cond(this.state)) {
		console.log('fun', 'stop');
		this.stop();
		return this.state;
	    } else {
		console.log('fun', 'go');
		this.fn(this.state);
	    }
	}
    }

    start () {
	let code = this.fun();
	console.debug('start', code)
	this.timer = setInterval(code, this.delay)
    }

    stop () {
	console.debug('stop')
	if (this.timer) {
	    clearInterval(this.timer);
	    this.timers.push(this.timer);
	    this.timer = null;
	} else {
	    console.debug('[invalid state]', this.timer, 'should not be null');
	}
    }
}

function todo () {
    console.log('?', new Date());
    document.body.innerHTML = new Date();
}

r = new Repeated(1000, s => s.stop === true, todo, { stop : false })

r.start()