typescript set default for a function passed as an argument to another function

Question

Is there a way to set a default for a function passed as an argument to another function. By default i mean a function that does absolutely nothing.

So i can check if the function argument value is null and assign it to an empty void function:

MyFunction(someVar:string,callback:()=>void){
 if(callback==null) {this.MyEmptyFunction();}else{callback();}

}

MyEmptyFunction():void{}

Is a way to avoid creating an empty function and the null check?

Titian Cernicova-Dragomir · Accepted Answer · 2018-05-07 09:39:07Z

3

You can set a default just as you would for any other parameter:

function MyFunction(someVar:string, callback = () => { }){
    callback();
}

Or with the argument type explicitly specified:

function MyFunction(someVar: string, callback: () => void = () => { }) {
    callback();
}

answered May 7, 2018 at 9:39

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