Benchmark: js object vs array

Script Preparation code:

var arr = []
for (var i = 0; i < 10000; i++) arr[i] = i
var obj = {}
for (var i = 0; i < 10000; i++) obj[i] = i

Tests:

arr
var sum = 0 for (var i = 0; i < 10000; i++) sum += arr[i]
obj
var sum = 0 for (var i = 0; i < 10000; i++) sum += obj[i]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arr
obj

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**What is being tested?**

The benchmark tests two approaches to perform basic arithmetic operations on large datasets: arrays and objects in JavaScript. The test cases are designed to measure the performance difference between these two data structures when performing a simple sum operation.

**Options compared:**

There are two options being compared:

1. **Arrays**: In this approach, a large array is created with 10,000 elements, each initialized with an incrementing value (from 0 to 9,999). The test case then iterates through the array, adding each element to a running sum.
2. **Objects**: Similar to the array approach, but instead of using an array, an object is created with 10,000 properties, each initialized with an incrementing value (from 0 to 9,999). The test case then iterates through the object's keys, adding each value to a running sum.

**Pros and cons:**

* **Arrays**: Pros:
	+ Access time is generally faster compared to objects.
	+ Can be more cache-friendly due to contiguous memory allocation.
* Cons:
	+ Key-based access can lead to slower performance due to hashing and lookup overhead.
* **Objects**: Pros:
	+ Dynamic property addition or removal can be useful in certain scenarios.
	+ Can provide better flexibility for complex data structures.
* Cons:
	+ Access time is generally slower compared to arrays.
	+ Not cache-friendly due to the need to hash keys.

**Library usage:**

There is no explicit library mentioned in the benchmark definition. However, it's worth noting that some JavaScript engines may use libraries or internal implementations that might affect the performance of these test cases.

**Special JS features or syntax:**

None are explicitly mentioned in this particular benchmark. However, it's essential to be aware of other JavaScript features and syntax that might impact performance, such as:

* **Array methods**: Methods like `forEach()`, `map()`, and `reduce()` can introduce additional overhead compared to manual iteration.
* **Object methods**: Methods like `for...in` and `hasOwnProperty()` can lead to slower performance due to the need to iterate through object properties or check for existence.

**Other alternatives:**

If you wanted to test other data structures, you could consider adding more test cases with:

* **Sets**: A collection of unique values that can provide faster lookups and insertions.
* **Maps**: An object-like structure that preserves key-value associations and provides efficient lookup, insertion, and deletion operations.

To explore alternative data structures, you would need to modify the benchmark definition by creating new script preparation code, HTML preparation code (if applicable), and test case definitions.

Related benchmarks:

js object vs array (version: 0)

Comparing performance of: arr vs obj

Created: 6 years ago by: Guest

Jump to the latest result

arr

obj

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):