Change Order of execution : Javascript

Asked Apr 16 '21 at 00:08

Active Apr 22 '21 at 18:59

Viewed 21 times

Here is the code.

commLib.commBegin = function (data) {

    var returnValue

    port.open(error => {
        if (error) {
            returnValue = [data[0], 'error', error]
            console.log('1-1')
        } else {
            returnValue = [data[0], 'completed']
            console.log('1-2')
        }
    })
    console.log('2')
    return returnValue
 }

I want to print data,

1-1 //or 1-2
2

but, If I execute this.

2
1-1 //or 1-2

I know Javascript is synchronous, but I want to know whether there is no way. And, if there is a way, please teach me.

edited Apr 22 '21 at 18:59

Mark Rotteveel

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asked Apr 16 '21 at 00:08

Teddy Bang

Why don't you log inside the callback? – Unmitigated Apr 16 '21 at 00:10
The open function is likely going to run after commBegin has finished. So don’t modify returnValue like this – evolutionxbox Apr 16 '21 at 00:12
`port.open` is not synchronous, that's why it has a callback function – charlietfl Apr 16 '21 at 00:17
@SuperStormer Thank for giving me the reference. I should go and read that. – Teddy Bang Apr 16 '21 at 00:20
@SuperStormer I have more question. If I want to return the returnValue, how should I do? In question, there is no example to return variable. – Teddy Bang Apr 16 '21 at 00:26
1

Yes, because you can't. You have to either use callbacks, promises, or any of the other various ways to return a value asynchronously. – SuperStormer Apr 16 '21 at 00:26
@SuperStormer Oh, I see. This is very difficult... Thank you. – Teddy Bang Apr 16 '21 at 00:30
@TeddyBang If you want to return a value have a look at: [How do I return the response from an asynchronous call?](https://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) – 3limin4t0r Apr 22 '21 at 19:09

Change Order of execution : Javascript

0 Answers0