var a = [1,2,3]; a[Symbol.asyncIterator] = function() { return { i: 0, next() { return new Promise((resolve, reject) => { setTimeout(()=>{ resolve({ value: a[this.i], done: ++this.i > a.length }); }, 1000) }); } } } async function ag(){ try{ for await(var x of a) { console.log(x); } } catch(e) { console.log(e);
} } ag();

(async function ag(){ try{ for await(var x of ['a', 'b', 'c']) { console.log(x); } } catch(e) { console.log(e);
} })();