How to import enum in interface declaration file (d.ts)

Question

I want to extend string with a method that needs an enumeration to be passed. How do I import that enum into the declaration file?

CapitalizationStyle.tsx:

export enum CapitalizationStyle {
    None = 0,
    Lowercase = 1,
    Word = 2
}

StringExtensions.d.ts:

import { CapitalizationStyle } from "Utils/CapitalizationStyle"; //This line breaks everything.

declare interface String {
    applyCapitalizationStyle(this: string, style: CapitalizationStyle): string;
}

The import breaks the interface declaration, like if the declaration does not exist anymore. All extension implementations of the String class become invalid as soon as I add the import:

StringExtensions.tsx:

Minimal reproducible example project: https://wetransfer.com/downloads/d1a707c0ac734985b877058967c35a6820171212143715/410f48

Can you more precisely explain "breaks everything"? Do you have a TSLint error? Is it by change "TS1192: <path> has no default export"? — msanford
– msanford, Commented Dec 7, 2017 at 18:39
I have added some more details in my original post to clarify this. This import breaks the whole file, like if none of the declarations (StringExtensions.d.ts) exist anymore, make all implementations invalid (StringExtension.tsx) — olivierr91
– olivierr91, Commented Dec 9, 2017 at 3:17

msanford · Accepted Answer · 2017-12-07 18:38:49Z

2

Since you don't have a default export from that module, you need to wrap it in {}:

import { CapitalizationStyle } from "Utils/CapitalizationStyle";

answered Dec 7, 2017 at 18:38

msanford

12.4k13 gold badges73 silver badges100 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

gsamaras Over a year ago

It seems that you were 10 secs faster than me! Bravo, +1!

olivierr91 Over a year ago

Thank you, but this is not the issue. I have added some more details in my original post. The problem is not with the import itself, but that it breaks the declaration completely.

msanford Over a year ago

@sixtstorm1 Thanks for adding detail. Can you make a plunkr?

olivierr91 Over a year ago

I have tried to make a plunkr but after fiddling around did not find how to make it work. I have added a link to a minimal reproducible example in my original post. The build will fail with Property 'applyCapitalizationStyle' does not exist on type 'String'. Remove the import from the d.ts (and remove the enum from the method signature), and it will build correctly.

olivierr91 Over a year ago

Well StringExtensions is used pretty much everywhere, I'm just adding methods to the prototype, so I can do something like: var str1 = 'joHn dOE'; console.log(str1.applyCapitalizationStyle(CapitalizationStyle.Word)); //Outputs 'John Doe'

|

gsamaras · Accepted Answer · 2017-12-07 18:49:56Z

0

Try wrapping in curly braces, like this:

import {CapitalizationStyle} from "Utils/CapitalizationStyle";

since you don't default-export your custom enumeration.

edited Dec 7, 2017 at 18:49

answered Dec 7, 2017 at 18:39

gsamaras

73.7k50 gold badges210 silver badges330 bronze badges

Collectives™ on Stack Overflow

How to import enum in interface declaration file (d.ts)

2 Answers 2

6 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related