I am a beginner to TypeScript. I read online that functions have a global scope by default in TypeScript.
So I have:
const addTwo = (num) => {return (num 2)};
in file1.ts and:
console.log(addTwo(4));
in file2.ts.
Then I transpile using tsc file1.ts file2.ts which works, but then when I try to run them using node talk1.js talk2.js nothing prints out. Why does this happen and how do I fix it? Thanks!
CodePudding user response：
If you want to use the global scope like this you need to execute both files in the same context. In the browser you could do that just by adding two <script> tags, in Node however, you would need to combine the files.
It is not recommended to do this because...
- You need to keep track of the correct order in which files are added
- You can easily get name conflicts because all top-level names share the same scope
- There is no built-in support for executing files like this in Node
I would recommend reading about the different module systems (Node originally only used CommonJS but now also supports ES modules) and using one of those. TypeScript has a module option for outputting the various module formats.
CodePudding user response：
what global scope means is global scope in the current file
If you want to use addTwo function from file1.ts in file2.ts
you should first export it:
// file1.ts
export const addTwo = (num) => {return (num 2)};
then import it in file2.ts
// file2.ts
import { addTwo } from './polyfills';
console.log(addTwo(4));
then compile file2.ts and run it
tsc file2.ts
node file2.js