Typescript 找不到声明文件

Question

Im not sure why but typescript cannot find my declaration file even though I have one. Can anyone see why this is?

My project structure:

scr
  - main.ts
  - dec.d.ts

str-utils
  - index.js

The import:

import {strReverse, strToLower} from '../str-utils/index.js' 

My declaration file (dec.d.ts):

declare module "str-utils"

My typescript config:

{
  "compilerOptions": {
    "module": "commonjs",
    "noImplicitAny": true,
    "removeComments": true,
    "preserveConstEnums": true,
    "sourceMap": false,
    "outDir": "dist"
  },
  "include": [
    "src/**/*",
    "src/dec.d.ts"
  ],
  "exclude": [
    "node_modules",
    "**/*.spec.ts"
  ]
}

Can anyone see what I am doing wrong here?

Answer 1

The general rule for the name of declare module "{name}" is that it should be the same name you would use to import the module. So, in this case, declare module '../str-utils/index.js' . But this will not work because declare module "{name}" doesn't work for relative paths. You have two options to solve this issue:

1. Making the import non-relative:

You modify the tsconfig to make str-utils available without a relative import.

{
  "compilerOptions": {
    // other options
    "paths": {
      "string-utils": ["./str-utils/index.js"]
    },
  },
  // other options
}

Now you can import str-utils via import {strReverse, strToLower} from 'str-utils' and thus, your module declaration works.

2. Moving the declaration file into the str-utils folder

First, you need to remove declare module "str-utils" from your declaration file. It should look something like this:

// no wrapping declare module "name" anymore
export function strReverse(arg: string): string;

export function strToLower(arg: string): string;

Then you need to rename the declaration file name to match the file name of the module you want to augment. In this example, we want to augment index.js , so the type declaration's file name should be index.d.ts . Your folder structure should look like that for this approach:

src
  - main.ts
  
str-utils
  - index.d.ts
  - index.js