🔎 Array.prototype.find() Polyfill
Category: js / polyfills
Difficulty: medium
The find() method returns the first element in an array that satisfies a provided testing function. If no element matches, it returns undefined. This polyfill supports the optional thisArg parameter for binding context. ✅ Implementation [code example] How It Works: Iteration : The customFind method iterates through the array using a for loop. Callback Execution : For each element, it calls the provided callbackFn with the current element, its index, and the array. If the callback returns a truthy value, the method immediately returns that element. Optional thisArg : If provided, thisArg is used to bind this inside the callback function using .call(thisArg, this[i], i, this). No Match : If no element satisfies the condition in callbackFn, it returns undefined. Example: customFind(element => element > 10) returns the first element greater than 10, which is 12. If no element matches, such as customFind(element => element > 200), it returns undefined. Why Use .call(thisArg, ...)? Explicit this Binding : The .call(thisArg, ...) ensures that the this value inside the callback is explicitly set to thisArg. This is crucial when thisArg is provided and the callback relies on it. Without .call(), the this value could be undefined (in strict mode) or the global object (non-strict mode), leading to unexpected results. By using .call(thisArg, ...), we guarantee that thisArg is used as the context inside the callback....