Performance Implications of Defining Methods via Prototype vs Constructor in JavaScript

In JavaScript, two approaches exist for creating "classes" with public functions: using the prototype or the constructor. Method 1 assigns functions to instances through the constructor, while Method 2 utilizes the prototype to share functions among all instances.

While Method 2 is often claimed to be more efficient, depriving instances of private instance variables is a significant disadvantage. However, does Method 1's apparent creation of duplicate function copies for each instance truly occur in practice?

Empirical Evidence from JsPerf Benchmark

JsPerf benchmarking suggests that Method 2 (prototype) indeed outperforms Method 1 (constructor) in terms of speed.

Practical Implications

While this difference is evident in benchmarks, its relevance in real-world applications is questionable. Even in scenarios with a significant number of object instantiations (e.g., 10,000 per frame), this micro-optimization is unlikely to alleviate performance bottlenecks.

Recommendations

If optimizing performance is crucial, declaring methods via the prototype is advisable. Otherwise, Method 1 provides greater flexibility and adheres to common object-oriented programming conventions. Additionally, the use of private properties denoted by an underscore prefix (e.g., _process()) enhances encapsulation and discourages direct modification.