import as variable and concatenation?

Question

I found this piece of code in github and I don't understand it

function writeClients(dictionary: IReferenceDirectory[]) {
//more code here

  let superClientFile = `import IClientOptions from './base/IClientOptions';\n`;
  superClientFile += `import Transport from './base/Transport';\n\n`;

source: https://github.com/Silind/twitter-api-client/blob/c8d724f38a9ed7112cd112ce11f2013f21b4740f/src/generator/writeClients.ts#L11

why don't the author import at the most top? What's the intention here? and he use += too

it seems like the code is generating a new js or ts file to be executed, whatever written in that file is going to be executed seperately. — tsamridh86, Oct 12 '20 at 07:50

score 0 · Answer 1 · answered Oct 12 '20 at 07:54

Looks like the library dynamically builds the TwitterClient class with fields and methods depending on the passed dictionary argument. At the end of the referenced file, you can see that the generated class is written to disk:

fs.writeFileSync(`${generatedPath}/index.ts`, superClientFile);

So it seems that this is a fancy way of generating the TwitterClient that can later be imported in your app. Also building the class content using += concatenation is considered the way to go nowadays, see JS strings "+" vs concat method for more information.

score 0 · Answer 2 · answered Oct 12 '20 at 07:59

It imports the selected files based on clients.

clients.forEach((client) => {
  superClientFile += `import ${client} from './clients/${client}';\n`;
});

And at the end of the file, it writes the code into the file index.ts so above two import lines should be included in superClientFile string. That is the code of file - index.ts

...
superClientFile += '}\n\nexport default TwitterClient;\n';
fs.writeFileSync(`${generatedPath}/index.ts`, superClientFile);

import as variable and concatenation?

2 Answers2