Describe and hint what parameters a function requires

Question

How can I describe what parameters my function requires and make them viewable when i type my code?

• For example, lets say I want to hint what parameters a callback function would take. If we look at ExpressJS render function below, it shows exactly what the callback accepts and would return.
• Mine however only says (cb1: any) despite that this callback is supposed to return 2 parameters (error and data). Is there any special way to define it?

Currently the code in my Product model for this function looks like this. How can I define the callback function in a way that it would hint what it returns?

static findById(id, cb1) {
 fs.readFile("./src/database/products.json", (err, data) => {
   if (err) {
     cb1(err, product);
   } else {
     const products = JSON.parse(data);
     const product = products.find(p => p.id == id);
     cb1(err, product);
   }
 });
};

Answer 1

Alright guys thanks for the help! It seems that just by using jsdocs without typescript is enough. I was not aware of how jsdocs works in vscode. After changing my code to the one bellow I got what I wanted. I will be playing with this more.

/**
* Finds a `product` with the given `id` and executes a callback `fn` containing the result.
* @param {number} id
* @param {(err : Error, product: string) => void} callback
*/
static findById(id, callback) {
  fs.readFile("./src/database/products.json", (err, data) => {
    if (err) {
      callback(err, product);
    } else {
      const products = JSON.parse(data);
      const product = products.find(p => p.id == id);
      callback(err, product);
    }
  });
};

Answer 2

Use :Javascript documentation starndards

OR You need to use Typescript for define functions interface:

static findById(id: number, cb1: (err: {}, product: {}) => void) {
 fs.readFile("./src/database/products.json", (err, data) => {
   if (err) {
     cb1(err, product);
   } else {
     const products = JSON.parse(data);
     const product = products.find(p => p.id == id);
     cb1(err, product);
   }
 });
};

Answer 3

This question might help you : jsdoc and vscode: Documenting a function passed as an argument to another function