Merge branch 'feature/add-polyfill-doc' of https://github.com/Codecademy/docs into feature/add-polyfill-doc

Author: SaviDahegaonkar

content/javascript/concepts/polyfill/polyfill.md

@@ -1,65 +0,0 @@
----
-Title: 'Polyfill'
-Description: 'A polyfill is JavaScript code that adds modern functionality to older browsers lacking native support, ensuring compatibility and consistent behavior.'
-Subjects:
-  - 'Computer Science'
-  - 'Developer Tools'
-  - 'Web Development'
-Tags:
-  - 'Developer Tools'
-  - 'Frameworks'
-  - 'Javascript'
-  - 'Programming'
-CatalogContent:
-  - 'introduction-to-javascript'
-  - 'paths/front-end-engineer-career-path'
----
-
-A **polyfill** is a small piece of JavaScript code that enables developers to use modern features in browsers that don’t natively support them, ensuring consistent functionality. It serves as a fallback strategy that adds newer features to older browser versions, making it easier for developers to use advanced methods, APIs, or syntax without worrying about browser compatibility. Polyfills are particularly beneficial when implementing cutting-edge functionality, as they allow a uniform user experience across different browsers and platforms. For example, if a browser doesn't support the `Array.prototype.includes` method, a polyfill can be used to manually add the feature, ensuring smooth operation of applications across multiple environments.
-
-## Syntax
-
-Here's the syntax for a polyfill that typically checks if a method or feature is already available, and if not, it defines the missing functionality:
-
-```pseudo
-if (!Feature.prototype.method) {
-  // Define the polyfill for the missing method
-  Feature.prototype.method = function() {
-    // Polyfill implementation
-  };
-}
-```
-
-- `feature`: The object, class, or prototype (like `String`, `Array`, `Object`, or custom objects) that is missing the method or functionality. The polyfill ensures this feature becomes available on it.
-- `method`: The specific method (e.g., `includes`, `assign`, etc.) that is missing and needs to be added by the polyfill.
-- `if (!Feature.prototype.method)`: Condition that checks if the method is missing in the current environment and only applies the polyfill if it's absent.
-
-## Example
-
-Here’s an example that demonstrates how a polyfill works by adding the missing `includes` method to the `Array` prototype:
-
-```js
-if (!Array.prototype.includes) {
-  // Polyfill for the 'includes' method
-  Array.prototype.includes = function (element) {
-    for (let i = 0; i < this.length; i++) {
-      if (this[i] === element) {
-        return true;
-      }
-    }
-    return false;
-  };
-}
-
-// Example usage of the polyfill
-const arr = [1, 2, 3, 4];
-console.log(arr.includes(3));
-console.log(arr.includes(5));
-```
-
-Here the code first checks if the `Array.prototype.includes` method exists. If it's missing, the polyfill defines it. The polyfill works by iterating through the array and returning `true` if the specified element is found, or `false` if it's not.
-
-```shell
-true
-false
-```