Generating IDs in array of objects.

generate-id.js

/*
    * This is just a module for generating IDs when you want mapping through array of objects (Useful in React JS).
    * Learn about generator functions here: https://javascript.info/generators
    * This code is made by using (Reavelling Design Pattern).
    * Learn about this pattern here (Arabic explain) : shorturl.at/jkUW4
*/

/*
   * File and name it: generate-id.js (feel free to name it as you want).
   * Best practice to put this file in folder and name it: utils.
*/

const generateID = (function () {
   /**
     * @returns {number}
   */
    function* getNumberID() {
        let count = 1;

        while (true) {
            yield count++;
        }
    }
    
   /**
     * @param  {Array} sourceArr=[] - array to check if it has objects or not.
   */
    function isArrayNotEmpty(sourceArr = []) {
        return sourceArr.length !== 0
    }

   /**
     * @param  {Array} dataArr=[] - array has objects and insert IDs into each one.
   */
    function insertIDIntoData(dataArr = []) {
        if (isArrayNotEmpty(dataArr)) {
            const counter = getNumberID();

            dataArr.forEach((row) => {
                // Check that if each element in the array is type of object or not.
                if (typeof row === "object") {
                    // Check if each object dose not have 'id' property and if not, then add 'id' property to this object.
                    if (!row.hasOwnProperty("id")) {
                        // row.id = counter.next().value; => you can use this instead of the coming.
                        // But the coming is the best to prevent any modifications in ID of each item in array (recommended).
                        Object.defineProperty(row, "id", {
                            value: counter.next().value,
                            writable: false,
                            enumerable: true
                        });
                    }
                } else {
                    throw new Error(`Array ${dataArr.name} must contain only object.`);
                }
            });
        } else {
            throw new Error("Array must not be empty of objects.");
        }
    }

    return {
        insert: insertIDIntoData
    }
})();

export default generateID.insert;

/* ================================================================= */

/* This is a file which contain array of object you want mapping through it */

/* Don't forget to import your module at the top of the file. */

import generateIDs from "../utils/generate-id.js";

/* Example */
const products = [
    { productName: "product 1", productPrice: "220" },
    { productName: "product 2", productPrice: "400" },
    { productName: "product 3", productPrice: "1000" },
    { productName: "product 4", productPrice: "80" },
    { productName: "product 5", productPrice: "100" },
];

/*
   * This is IIFE which is called by itself.
   * You can use arrow function to run the generator as you see.
*/

(() => generateIDs(products))();

/* You can see the IDs in each products by logging the products array. */
console.log(products);