memorize promise

gistfile1.txt

// assume retry if promise is rejected, with a ttl feature

function promiseTest() {
	return new Promise((resolve, reject) => {
		setTimeout(() => {
			// console.log('promise done')
			if(Date.now()%2)
				resolve('ok')
			else
				reject('not ok')
		}, 3000)
	})
}
function memoize(method, ttl=60*60) {
	let cache = {}, expire = {};

	return async function() {
		let args = JSON.stringify(arguments);
		if(cache[args] && cache[args].isResolved && Date.now() < expire[args]){
			return cache[args]
		}
		cache[args] = method.apply(this, arguments);
		expire[args] = Date.now() + ttl * 1000
		cache[args].then(val => { cache[args].isResolved = true; return val})
		return cache[args];
	};
}

a = memoize(async function() {
	return promiseTest()
})