FAQ: Custom Types - Generic Functions

Frequently Asked Questions JavaScript FAQ
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This community-built FAQ covers the “Generic Functions” exercise from the lesson “Custom Types”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Learn TypeScript

FAQs on the exercise Generic Functions

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When running tsc with the generic function:

function getFilledArray<T>(value: T, n: number): T[] { return Array(n).fill(value);

The following error pops up:

index.ts:2:19 - error TS2550: Property ‘fill’ does not exist on type ‘any’. Do you need to change your target library? Try changing the ‘lib’ compiler option to ‘es2015’ or later.

Is the get filleArray function conceptually wrong?

3

Are you running tsc in Codecademy environment?

If so, what does the tsconfig.json file show? (you can click on the folder icon in the top left corner of the editor to view the file)

Mine shows:

{
  "compilerOptions": {
    "target": "es2017",
    "module": "commonjs",
    "strictNullChecks": true
  },
  "include": ["**/*.ts"]
}

and it doesn’t throw the error mentioned by you.

Related links about tsconfig:

4

Yes, I am in the Codeacademy environment, and my tsconfig file is the same:

image
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Now, if I run:
ts --target es2015 index.ts

as suggested in the StackOverflow link that you sent, I get no error messages
Thank you

1 Like