Akash Akash - 1 year ago 108
TypeScript Question

Arrow function in typescript interface with return type as void

I am trying to write arrow function in my type Script interface as below but getting error "Class 'ToastrService' incorrectly implements interface 'IToastr'."

interface IToastr{

export class ToastrService implements IToastr {
(message:string,title:string):void {

My question is: can we define a function signature in TS interface with return type as void??

I did try searching google as well but did not find any example. Thanks !!

Answer Source

Yes it is possible. Please consult the official typescript for more info.

Example 1:

interface SearchFunc {
    (source: string, subString: string): void;
let mySearch: SearchFunc;
mySearch = function(source: string, subString: string) {
    // do smth

Example 2: Solution: You should name your function

interface IToastr{

class ToastrService implements IToastr {
    FuncName(message:string,title:string):void {
         // toastr.success(message,title);
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