TypeScript optional callback parameter does not match anonymous function passed to it

Question

I have a simple problem with my TS callbacks.

I have a function like this

...
//inside a class
    //function is supposed to optionally accept any callback function
    refreshConnection(callback?:Function) {
        //do something
        //then call the passed callback with no params
        callback();
    }

...

//in another component, i call this function like so
this.myclass.refreshConnection( () => {
    window.location.reload();
});

//but i get an error saying that the function parameter does not match a signature.

// i also tried callback?: (...args: any[]) => any but nothing.


ERROR in ./src/app/fb_connect.component.ts
Module build failed: Error: /var/www/mysite/frontend/angular2/src/app/fb_connect.component.ts (70,41): Supplied parameters do not match any signature of call target.)
    at _checkDiagnostics (/var/www/mysite/frontend/angular2/node_modules/@ngtools/webpack/src/loader.js:115:15)
    at /var/www/mysite/frontend/angular2/node_modules/@ngtools/webpack/src/loader.js:140:17
 @ ./src/app/app.module.ts 15:0-51
 @ ./src/app/index.ts
 @ ./src/main.ts

Note: (70,41) is the function call for refreshConnection. Commenting it out fixes the problem

I cannot reproduce. Could you try to use that site to reproduce your error, then edit your question to add the link? — Madara's Ghost
– Madara's Ghost, Commented Jan 12, 2017 at 22:22
Are you using resharper? I get so many incorrect errors like this with resharper... it's ridiculous. I sometimes navigate files with a sea of red. — David Sherret
– David Sherret, Commented Jan 12, 2017 at 22:30
I dont use resharper, at least not knowingly. The project is an Angular 2 app, and i compile it using "ng build" tool...which in turn uses webpack. I added the error code to the original post. Note: when i comment out the function call, everything works fine. I also tried emptying out the function( having a blank function that does nothing. ) I think the compiler maybe giving me a wrong line number. — Rainer Plumer
– Rainer Plumer, Commented Jan 12, 2017 at 22:56

Jean-François Fabre · Accepted Answer · 2019-11-09 20:08:51Z

8

This snippet seems to be working fine:

class MyClass {

    public refreshConnection(callback?: Function) {

        if (callback) {
            callback();
        }
    }
}

let obj = new MyClass();
obj.refreshConnection(() => { console.log('It works!'); });

edited Nov 9, 2019 at 20:08

Jean-François Fabre♦

141k24 gold badges179 silver badges246 bronze badges

answered Jan 12, 2017 at 22:28

Uzair Sajid

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