Posted on Jul 13, 2023

Day 4: Polyfill for Object.keys()

Today, we'll create a polyfill for the Object.keys() method. The Object.keys() method returns an array of a given object's own enumerable property names. Our goal is to create a function called myKeys that will implement this behavior.

// Test case const obj = { name: "Bob", age: 1000 }; console.log(Object.myKeys(obj)); // Output: ["name", "age"]

Plan

To solve this problem, we'll follow these steps:

Implement the myKeys function to retrieve the enumerable property names of the object.
Use a loop or a built-in method to iterate over the object's properties and collect the keys.
Return an array containing the collected keys.
Check if the Object.myKeys property exists.
If it doesn't exist, create a new property called myKeys on Object and assign it a function.

Top comments (1)

Dharan Ganesan • Jul 11 '23

 // Check if Object.myKeys exists if (!Object.myKeys) { Object.myKeys = function (obj) { // Create an array to store the keys const keys = []; // Iterate over the object's properties for (let key in obj) { // Check if the property belongs to the object and is not inherited if (obj.hasOwnProperty(key)) { // Add the key to the keys array keys.push(key); } } return keys; }; } // Test case const obj = { name: "Bob", age: "1000" }; console.log(Object.myKeys(obj)); // Output: ["name", "age"]