This benchmark compares two approaches for safely accessing nested properties in a JavaScript object and handling the case where the properties might be undefined or nonexistent. Specifically, it evaluates the use of the nullish coalescing operator (??) combined with optional chaining (?.), versus traditional conditional statements in an if structure to achieve similar functionality.

Test Cases Overview

1. Nullish Coalescing with Optional Chaining (nullish Test)

   const myObj = {};
   const myFunc = (param) => param?.key?.nestedKey ?? [];
   
   for (let i = 0; i < 1e6; i++) {
       myFunc(myObj);
   }
   

   • Explanation: This test uses the optional chaining operator (?.), which allows for safe access to nested properties. If any part of the chain returns undefined or null, the evaluation short-circuits and ends, returning undefined. The nullish coalescing operator (??) then provides a fallback value of an empty array [] if the entire expression yields undefined.
   • Pros:
     • Concise and easier to read.
     • Reduces boilerplate code for checking nested properties.
     • Straightforward handling of default values.
   • Cons:
     • May have slightly higher overhead in terms of function calls or complexity for very deep structures, depending on the underlying JavaScript engine's optimization.

2. Traditional If-Else Conditional (if Test)

   const myObj = {};
   const myFunc = (param) => {
       if (!param.key) return [];
       if (!param.key.nestedKey) return [];
       
       return param.key;
   };
   
   for (let i = 0; i < 1e6; i++) {
       myFunc(myObj);
   }
   

   • Explanation: This test uses standard if statements to check each level of the object's nested properties manually. If any of the conditions fail, it returns an empty array.
   • Pros:
     • More explicit and may be easier to understand for developers unfamiliar with modern JavaScript features.
   • Cons:
     • More verbose and hence potentially more prone to bugs or maintenance difficulties.
     • Can lead to longer code and less readability.

Benchmarking Results

• The benchmark results show the performance of both tests executed 1,000,000 times.
  • The if test had 489.52 executions per second.
  • The nullish test recorded 472.68 executions per second.

Both methods performed similarly, although the if construct showed a marginally better execution rate in this test. However, the slight difference in execution speed may not justify opting for verbosity over conciseness in most scenarios.

Considerations and Alternatives

Choosing between these approaches can depend on the context and preferences. Here are some considerations:

• Readability vs. Performance: In scenarios where code maintainability and clarity are prioritized, the nullish coalescing with optional chaining may be preferred despite being slightly slower. This is especially true for teams working with varying levels of JavaScript expertise.

• Legacy Browser Support: It's also important to note that optional chaining and nullish coalescing are features introduced in ES2020. If the targeted execution environment does not support these features (e.g., older browsers or JavaScript engines), the if-else structure may be a requirement.

• Error Handling: The traditional method allows for more complex scenarios where logging or specific error handling might be necessary. Conversely, optional chaining may not give the developer much insight into where the access failed.

• Other Alternatives: In addition to these methods, there are libraries such as Lodash that provide utility functions like _.get() for safely accessing deeply nested properties without additional boilerplate, offering both safety and conciseness.

In conclusion, both the nullish coalescing with optional chaining method and the traditional if-else method have valid use cases, and the choice between them may depend on team standards, project requirements, and considerations about readability versus performance.