Benchmark: spread vs mutation vs Object.assign for reduce callback (30)

Tests:

with spread operator
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push(x) } return output } range(0, 30).reduce((acc, num) => { return { ...acc, [num]: num } }, {})
with mutation
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push(x) } return output } range(0, 30).reduce((acc, num) => { acc[num] = num return acc }, {})
with object assign
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push(x) } return output } range(0, 30).reduce((acc, num) => { return Object.assign(acc, {[num]: num}) }, {})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
with spread operator
with mutation
with object assign

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 benchmark and explain what's being tested.

The provided benchmark defines three test cases:

1. **Spread Operator** (`"with spread operator"`): This test case creates an array `output` using a function `range`, which generates numbers from 0 to 30. Then, it uses the spread operator (`...`) to create a new object with the numbers as properties and values.
2. **Mutation** (`"with mutation"`): Similar to the first test case, this one creates an array `output` using the same function `range`, but instead of creating a new object, it mutates the existing accumulator object `acc` by assigning each number as a property with its value.
3. **Object.assign** (`"with object assign"`): This test case uses the `Object.assign()` method to create a new object with the numbers as properties and values.

The benchmark is testing which approach is faster: using the spread operator, mutating the accumulator object, or using `Object.assign()`.

Now, let's discuss the pros and cons of each approach:

* **Spread Operator**: This approach creates a new object every time it's called. While this can be efficient for small objects, it can lead to memory overhead for large datasets.
* **Mutation**: This approach modifies an existing accumulator object, which can be less memory-efficient than creating a new object. However, it avoids the overhead of `Object.assign()` and might be faster in terms of iteration.
* **Object.assign()**: This approach creates a new object every time it's called, similar to the spread operator. It's generally safe but can lead to memory issues for large datasets.

**Other Considerations:**

* The benchmark uses JavaScript engines like Chrome 84 on Mac OS X 10.15.3.
* The test cases use relatively small arrays (numbers from 0 to 30), which might not be representative of real-world scenarios where larger datasets are involved.
* The `range` function generates numbers using a simple loop, which is straightforward but not particularly optimized.

**Library and Special JS Features:**

There's no explicit library used in these test cases. However, the spread operator is a built-in JavaScript feature introduced in ECMAScript 2018.

**Benchmark Preparation Code:**

The provided JSON does not contain any script preparation code. The benchmark definition itself is enough to execute the tests.

Related benchmarks:

spread vs mutation vs Object.assign for reduce callback (30) (version: 0)

Comparing performance of: with spread operator vs with mutation vs with object assign

Created: 7 years ago by: Guest

Jump to the latest result

with spread operator

with mutation

with object assign

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):