Compatibility with Node 20: NodeJS.Timer vs NodeJS.Timeout

[fabian-paus]

``There seems to be a compatibility issue when using emailjs with Node 20 and TypeScript, since the Timeout interface has a new dispose method:

../node_modules/emailjs/smtp/client.ts:165:17 - error TS2769: No overload matches this call.
  Overload 1 of 2, '(timeoutId: string | number | Timeout | undefined): void', gave the following error.
    Argument of type 'Timer' is not assignable to parameter of type 'string | number | Timeout | undefined'.
      Property '[Symbol.dispose]' is missing in type 'Timer' but required in type 'Timeout'.
  Overload 2 of 2, '(id: number | undefined): void', gave the following error.
    Argument of type 'Timer' is not assignable to parameter of type 'number'.

165    clearTimeout(this.timer);
                    ~~~~~~~~~~

  ../node_modules/@types/node/timers.d.ts:126:17
    126                 [Symbol.dispose](): void;
                        ~~~~~~~~~~~~~~~~
    '[Symbol.dispose]' is declared here.


Found 1 error in ../node_modules/emailjs/smtp/client.ts:165

The issue seems to be cause by the type annotation in client.ts

protected timer: NodeJS.Timer | null = null;

The type NodeJS.Timer is a legacy type that does not have the dispose method.
Later the setTimeout method actually returns a NodeJS.Timeout (with the required dispose method).
The error is caused by the clearTimeout call, that requires a NodeJS.Timeout but is given a NodeJS.Timer:

if (this.timer != null) {
    clearTimeout(this.timer);
}

Potential fix: Annotate timer with the correct type

protected timer: NodeJS.Timeout | null = null;

Or potentially be more generic:

protected timer: ReturnType<typeof setTimeout> | null = null;

Versions:

• Node: v20.5.1
• @types/node: 20.5.9
• emailjs: 4.0.2

[eleith]

awesome. thanks for the breakdown. will resolve with one of your suggestions.