<pre class="shiki github-dark shaku"><code>/** * @param {object} obj * @param {object} target * @return {boolean} */ function myInstanceOf(obj, target) { // If the object does not exist or we've reached the base Object constructor, return false if(!obj || typeof obj !== 'object') return false ​// Check if the target is a valid object ​if(!target.prototype) throw Error ​// If the object's prototype matches our target's prototype, return true ​// Otherwise, recurse down the prototypal chain ​if(Object.getPrototypeOf(obj) === target.prototype) { ​return true ​} else { ​return myInstanceOf(Object.getPrototypeOf(obj), target) ​}}</code></pre>

Solution using the getPrototypeOf method (w/ comments)

Do you know how instanceOf works ? If so, please write you own myInstanceOf(). class A {}class B extends A {}const b = new B()myInstanceOf(b, B) // tr…