Environment variable is not assigning with Typescript

Question

My code is:

const port: Number = process.env.PORT || 3000;

[ts]
Type 'string | 3000' is not assignable to type 'Number'.
  Type 'string' is not assignable to type 'Number'.

I tried

const port: Number = parseInt(process.env.PORT, 10) || 3000;

But it gives me another error:

Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
  Type 'undefined' is not assignable to type 'string'.
(property) NodeJS.Process.env: NodeJS.ProcessEnv

What am I doing wrong?

It's complaining about the argument you're passing to parseInt, which may be undefined but must be a string. I think you want parseInt(process.env.PORT || '3000', 10). — jonrsharpe
– jonrsharpe, Commented May 16, 2018 at 17:06

Shamoon · Accepted Answer · 2018-05-17 20:26:58Z

36

const port: Number = parseInt(<string>process.env.PORT, 10) || 3000

This solved it. I think it's called Type Assertion

answered May 17, 2018 at 20:26

Shamoon

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2 Comments

lmat - Reinstate Monica Over a year ago

I think that's not correct? process.env.PORT could be string, or it could be undefined. You're asserting that it can't be undefined here which is false. As the comment-answer above says, you should parseInt(process.env.PORT || '3000') to cover the case when process.env.PORT is undefined.

Stanley Over a year ago

You can also do: const port: Number = parseInt(`${process.env.PORT}`, 10) || 3000 which will ensure a string is passed to parseInt.

Jopinsky · Accepted Answer · 2022-06-14 09:03:35Z

3

I usually do this.

const PORT = Number(process.env.PORT ?? 3000);

answered Jun 14, 2022 at 9:03

Jopinsky

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1 Comment

Community Over a year ago

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Bestin John · Accepted Answer · 2021-07-22 01:05:48Z

2

This should work as well.

const port: Number = parseInt(process.env.PORT as string, 10) || 3000

answered Jul 22, 2021 at 1:05

Bestin John

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