p1 = new Promise((res,rej)=>{ console.log("p1 setTimeout"); setTimeout(()=>{ res(17); }, 10000); }); p2 = new Promise((res,rej)=>{ console.log("p2 setTimeout"); setTimeout(()=>{ res(36); }, 2000); }); function checkIt() { console.log("Started"); let val1 = this.p1; console.log("P1"); val1.then((data)=>{console.log("P1 => "+data)}); let val2 = this.p2; console.log("P2"); val2.then((data)=>{console.log("P2…
At which point during the JavaScript event loop does it figure out that a timer has reached its target time and needs to be placed on the macroQueue? Does it do this check after completing each macroQueue/microQueue task, or after…
Based on this accepted answer regarding micro-task queue checkpoints in JS and looking up the concept more, I have come to understand the following: Micro-task queue checkpoints happen at these points in the event loop: After a script execution: When…
I was reading this blog about event loop and micro/macrotask queues in javascript but I have doubts about the statements from the blog: In JavaScript, no code is allowed to execute until an event has occurred. It is worth mentioning…
I'm a beginner. Got confused about async programming after seeing the output of this code async function f1() { console.log('this is f1'); let res = await f3(); console.log('result of f1 from f3 = ', res['status']); console.log('end of f1'); } async…
Recently I've stumbled upon an interesting bug. In the essence, the problem boils down to this example: const waitResolve = (ms) => new Promise((resolve) => { setTimeout(() => { console.log(`Waited to resolve for ${ms}ms`); resolve(ms); }, ms); }); const waitReject…
I just started exploring Node JS event-driven architecture and event loop, What I understand is that Event emitters enter into the Event Loop which should be asynchronous but when I execute below I see event emitters are logged first and…
Today I was asked this question on an interview. I couldn't answer this question and the interviewer said there was a special queue for requestAnimationFrame callbacks. But I can't find any information on this. If rAF has it's own queue…
console.log("11111"); setTimeout(() => { console.log("22222"); }, 5000); Promise.resolve().then(() => { console.log("33333"); }); document.getElementById("test").addEventListener("click", () => { console.log("44444 +"); }); // 10 sec sync delay. This gives me enough time to stack them into appropriate Queues. const syncWait = (ms) =>…
I have this bit of code: setTimeout( () => console.log("setTimeout callback is complete"), 0); fetch("https://api.coingecko.com/api/v3/ping") .then(() => console.log("fetch callback is complete")); // busy-wait for a few seconds: for (let i = 0; i < 1000000; i++) { for (let j…