variable changed before modifiying it in js async function

Asked Apr 23 '21 at 12:27

Active Apr 23 '21 at 12:27

Viewed 22 times

...
  const a = {
    data: { records: [1, 2, 3] },
  };

  const asyncfunction = (prop) => {
    return new Promise((resolve) => {
      setTimeout(() => {
        resolve(prop);
      }, 500);
    });
  };
  const fetch = async () => {
    const res1 = await asyncfunction(a);
    console.log(res1); //output 1,2,3,11111
    a.data.records.push(11111);
  };

  useEffect(() => {
    fetch();
  }, []);

I created a test component to demonstrate this. I thought the console.log will catch the result of await expression immediately and output 1,2,3. How come it becomes 1,2,3,11111 even before I modified it?

asked Apr 23 '21 at 12:27

ryan

Read this: https://stackoverflow.com/questions/23392111/console-log-async-or-sync – IAmDranged Apr 23 '21 at 12:33
cause it is how javascript work. event loop – elpmid Apr 23 '21 at 12:34
@elpmid Uhm, no, this is not how Javascript works… – deceze Apr 23 '21 at 12:36
or the nature? of how event loops works? – elpmid Apr 23 '21 at 12:36
every async process is send on the javascript runtime before sent to the event looop? – elpmid Apr 23 '21 at 12:38
@elpmid No idea what you're talking about… The array does not contain values which are pushed into it on the following line. Javascript isn't *that* async. – deceze Apr 23 '21 at 13:00
then i dont have idea what you talking about too – elpmid Apr 23 '21 at 13:07

variable changed before modifiying it in js async function

0 Answers0