Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

Benchmark Definition The benchmark is designed to compare two approaches: switch statements and using an object map (LUT) with early exit conditions. The test case uses a simple scenario where it takes an input string and checks if it matches one of 10 predefined values.

Options Compared

1. Switch Statement: The first option, labeled "Switch", tests the performance of a traditional switch statement. This approach is straightforward but can be slower due to the overhead of branching instructions.
2. Object Map (LUT): The second option, labeled "Map", uses an object map (LUT) with early exit conditions. This approach takes advantage of JavaScript's hash table implementation and can be faster than a traditional switch statement.

Pros and Cons

• Switch Statement:
  • Pros: Easy to understand and maintain.
  • Cons: Can be slower due to branching instructions.
• Object Map (LUT):
  • Pros: Can take advantage of JavaScript's hash table implementation for faster lookups.
  • Cons: Requires a predefined object with all possible values, which can be cumbersome if the number of cases is large.

Library and Its Purpose The LUT (Lookup Table) object is used to store the precomputed results for each input value. This allows for fast lookups using the object's hash table implementation. The purpose of this library is to provide a way to speed up the comparison process by reducing the number of branching instructions.

Special JS Feature or Syntax There are no special JavaScript features or syntax used in this benchmark.

Other Alternatives

• Regex: Another approach to compare performance would be to use regular expressions (regex) to match the input string against a set of predefined values. This approach can be more flexible but may also be slower due to regex overhead.
• Array Lookups: Using an array with indexOf() or includes() methods could be another alternative to compare performance. However, this approach would require creating an array with all possible values, which might be cumbersome if the number of cases is large.

In summary, the benchmark compares two approaches: traditional switch statements and using an object map (LUT) with early exit conditions. The LUT approach takes advantage of JavaScript's hash table implementation for faster lookups but requires a predefined object with all possible values.