Pass variable from function in Typescript

Question

I want to pass a value from the function to outside in Typescript.

I have tried many method, e.g. thing to declare global variables, return function value, etc, but it doesn’t work.

I think maybe my syntax is wrong. Could you please have a help? Code as below for reference. Many thanks.

    this.platform.ready().then(() => {

        FCMPlugin.getToken(
                    function (token) {
                        console.log(token);
                    },
                    function (err) {
                        console.log('error retrieving token: ' + err);
                    }
        );

        console.log(token); //I would to pass the token value to here
    }

There is no way to move the code inside the success callback? It seems to me it will run your code before even getting the token possibly. — Sami Kuhmonen, Sep 24 '16 at 17:27
Possible duplicate of [How do I return the response from an asynchronous call?](http://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) — Tamas Hegedus, Sep 24 '16 at 20:07

Francesco · Answer 1 · 2016-09-25T09:36:24.497

0

What about define an external var?

Like this:

    this.platform.ready().then(() => { 

var myToken;

    FCMPlugin.getToken(
                function (token) {
                    console.log(token);

myToken= token;

                },
                function (err) {
                    console.log('error retrieving token: ' + err);
                }
    );

    console.log(myToken); //I would to pass the token value to here
}

If getToken is async, u could trigger an event or do a callback

    this.platform.ready().then(() => { 


    FCMPlugin.getToken(
                function (token) {
                    console.log(token);
                    myCallback(token);
                    $('html').trigger('tokenReady',token);
                },
                function (err) {
                    console.log('error retrieving token: ' + err);
                }
    );

  function myCallback(myToken){

    console.log(myToken);

  }

}

$('html').on('tokenReady',function(e,token){

myCallback(token);

});

third version (callback only):

    this.platform.ready().then(() => { 


    FCMPlugin.getToken(
                function (token) {
                    console.log(token);
                    myCallback(token);
                },
                function (err) {
                    console.log('error retrieving token: ' + err);
                }
    );

  function myCallback(myToken){

    console.log(myToken);

  }

}

edited Sep 25 '16 at 09:36

answered Sep 24 '16 at 17:25

Francesco

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4
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That won't work if `getToken` is asynchronous because the `console.log` statement will run before the assignment to `myToken`. – David Sherret Sep 24 '16 at 17:32
Then you should use a callback or trigger an event (I edited) – Francesco Sep 24 '16 at 17:45
Many thanks ! but seems there are some typescript errors. [ts] can’t find $ [ts] can’t find name ‘myCallBack’ – Galaxy Lam Sep 25 '16 at 07:15
Mine was just an example, you shoud refactor it as your needs (the $ error is becasue you are not using jQuery lib and myCallback error is becasue myCallback is defined in another block) – Francesco Sep 25 '16 at 09:34
BTW I added a third versione with callback only that shoul give u no errors – Francesco Sep 25 '16 at 09:36
@GalaxyLam if it is what u were searching for accept it then :) – Francesco Sep 25 '16 at 17:31

score 0 · Answer 2 · answered Sep 24 '16 at 22:50

FCMPlugin.getToken

Executes asynchronously so you will not have a value for token until you hit the get token callback.

Additionally as it executes asynchronously, your second console.log statement will fire before your callback so you will not have any way of reaching the token value as it has not been returned at that point.

Simple answer is to move your code to handle the returned token inside your success callback where you have your first console.log statement.

Pass variable from function in Typescript

2 Answers2