Benchmark: Destructuring vs Key access

Tests:

Key access
const arr = []; for (let idx = 0; idx < 5000; idx++) { arr.push({ id: idx, emailAddress: `${idx}@email.com` }); } arr.reduce((result, current) => { result[current.emailAddress] = current; return result; }, {});
Destructuring
const arr = []; for (let idx = 0; idx < 5000; idx++) { arr.push({ id: idx, emailAddress: `${idx}@email.com` }); } arr.reduce((result, current) => { return { ...result, [current.emailAddress]: current }; }, {});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Key access
Destructuring

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's dive into the Benchmark Definition and explain what's being tested.

**What is being tested?**

The provided JSON represents two individual test cases for measuring JavaScript microbenchmarks on MeasureThat.net. The benchmark tests two different approaches to reducing an array of objects:

1. **Key access**: This approach uses the `arr.reduce()` method with a callback function to iterate over each object in the array and store it in a new object using bracket notation (`arr[current.emailAddress] = current;`).
2. **Destructuring**: This approach uses destructuring assignment to extract properties from objects into a new object, which is then returned by the `reduce()` method (`{ ...result, [current.emailAddress]: current };`).

**Options compared**

The two approaches are being compared in terms of performance, specifically the number of executions per second (ExecutionsPerSecond) measured on a Chrome 101 browser running on a Mac OS X 10.15.7 operating system.

**Pros and Cons:**

1. **Key access**:
	* Pros: This approach is more straightforward and easier to understand for developers familiar with bracket notation.
	* Cons: It may lead to slower performance due to the overhead of using `arr[current.emailAddress] = current;` which involves a property lookup, assignment, and potential object resizing.
2. **Destructuring**:
	* Pros: Destructuring can be more efficient since it avoids the overhead of property lookup and assignment.
	* Cons: This approach requires knowledge of destructuring syntax, which might make it harder to understand for developers without experience with this feature.

**Library used**

Neither of the test cases uses any external libraries or dependencies beyond the JavaScript language itself. However, `reduce()` is a built-in JavaScript method that comes with the standard library, so no additional imports are required.

**Special JS features or syntax**

The **destructuring assignment** in the second approach utilizes a feature called "object destructuring," which allows you to extract properties from objects into new variables. This feature was introduced in ECMAScript 2015 (ES6) and is widely supported by modern JavaScript engines.

**Other alternatives**

If you were considering alternative approaches for reducing an array of objects, some other options might include:

* Using `forEach()` or `map()` instead of `reduce()`, although this would likely have different performance characteristics.
* Implementing a custom reduction function using loops and conditional statements, which could be slower than the built-in `reduce()` method.

Keep in mind that these alternative approaches may not provide comparable results to the benchmarked methods, so MeasureThat.net's primary purpose is to compare existing JavaScript implementation choices.

Related benchmarks:

Destructuring vs Key access (version: 0)

Comparing performance of: Key access vs Destructuring

Created: 3 years ago by: Guest

Jump to the latest result

Key access

Destructuring

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):