Benchmark: compare the ways to generate an array filled with empty objects for iteration 2

compare the ways to generate an array filled with empty objects for iteration 2 (version: 1)

- Array.push - Array.apply: Array.apply(null, Array(100)) - Destructuring operator: [...Array(100)] - Array.prototype.fill Array(100).fill(undefined) - Array.from Array.from({ length: 100 })

Comparing performance of: Array.apply(null, Array(n)) vs [...Array(n)] vs Array(n).fill(null) vs Array.from({ length: n }) vs Array.from({ length:n }, (item, i) => i) vs Array.push vs Array with length + push vs new Array.fill(null)

Created: 2 months ago by: Guest

Jump to the latest result

Tests:

Array.apply(null, Array(n))
Array.apply(null, Array(1000)).map(() => ({}));
[...Array(n)]
[...Array(1000)].map(() => ({}));
Array(n).fill(null)
Array(1000).fill(null).map(() => ({}));
Array.from({ length: n })
Array.from({ length: 1000 }).map(() => {});
Array.from({ length:n }, (item, i) => i)
Array.from({ length:1000 }, () => {});
Array.push
const arr = [] for (let i = 0; i < 1000; ++i) arr.push({})
Array with length + push
const arr = new Array(1000); for (let i = 0; i < 1000; ++i) arr.push({})
new Array.fill(null)
new Array(1000).fill(null).map(() => ({}));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.apply(null, Array(n))
[...Array(n)]
Array(n).fill(null)
Array.from({ length: n })
Array.from({ length:n }, (item, i) => i)
Array.push
Array with length + push
new Array.fill(null)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36

Browser/OS: Chrome 132 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.apply(null, Array(n))	152088.0 Ops/sec
[...Array(n)]	188454.2 Ops/sec
Array(n).fill(null)	198871.3 Ops/sec
Array.from({ length: n })	40026.1 Ops/sec
Array.from({ length:n }, (item, i) => i)	35139.2 Ops/sec
Array.push	337739.4 Ops/sec
Array with length + push	269604.0 Ops/sec
new Array.fill(null)	201916.1 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the JSON provided tests various methods of generating an array filled with empty objects. The goal is to compare different JavaScript array creation techniques in terms of execution speed. Below are the options compared, along with their pros, cons, and other considerations.

### Options Compared:

1. **Array.push**
   - **Benchmark Definition**: `const arr = [] for (let i = 0; i < 1000; ++i) arr.push({})`
   - **Description**: This method involves creating an empty array and then using a loop to fill it with new object literals.
   - **Pros**: 
     - Straightforward and easy to understand.
     - Provides full control over the process.
   - **Cons**: 
     - Might be slower for large arrays due to the repeated operation of pushing to the end.
     - Involves mutation of the array object during iteration.

2. **Array with length + push**
   - **Benchmark Definition**: `const arr = new Array(1000); for (let i = 0; i < 1000; ++i) arr.push({})`
   - **Description**: Similar to the previous method but preallocates the array length before pushing objects.
   - **Pros**:
     - Preallocating can improve performance by avoiding dynamic resizing.
   - **Cons**:
     - The initial length is not utilized effectively since the array occupied by `push` is still dynamic.

3. **Array.apply**
   - **Benchmark Definition**: `Array.apply(null, Array(1000)).map(() => ({}));`
   - **Description**: Creates a new array by invoking the `apply` method to spread an array of specified length.
   - **Pros**:
     - Concise way to create an array from a defined length.
   - **Cons**:
     - Performance can suffer due to internal workings of `apply`.
     - May be less readable for those unfamiliar with the concept.

4. **Destructuring operator**
   - **Benchmark Definition**: `[...Array(1000)].map(() => ({}));`
   - **Description**: Uses the spread operator to create an array and fills it by mapping.
   - **Pros**:
     - Very readable and modern syntax.
   - **Cons**:
     - May incur performance overhead due to additional spread operation.

5. **Array.prototype.fill**
   - **Benchmark Definition**: `Array(1000).fill(null).map(() => ({}));`
   - **Description**: Initializes an array of a specified length, fills it with `null`, and then maps over it to create objects.
   - **Pros**:
     - Simple and utilizes built-in methods effectively.
   - **Cons**:
     - Initially fills the array with null values, which might be inefficient if mapping is the next step anyway.

6. **Array.from**
   - **Benchmark Definition**: `Array.from({ length: 1000 }).map(() => ({}));`
   - **Description**: Creates an array from an array-like object with a mapping function.
   - **Pros**:
     - Very readable and consistent with functional programming paradigms.
   - **Cons**:
     - Slightly lower performance compared to simpler array creation techniques.

7. **Array.from with mapping on creation**
   - **Benchmark Definition**: `Array.from({ length:1000 }, () => {});`
   - **Description**: Similar to the previous method but employs a mapping function directly in the creation.
   - **Pros**:
     - Efficient as it eliminates the need for a second mapping step.
   - **Cons**:
     - Obscurity might arise from using both the length and a mapping function together.

### Other Alternatives:
- **Using a native loop**:
  - For large arrays, traditional loops (like `for` or `while`) might outperform functional approaches.
  
- **Using **`Array.fill`** alongside object creation**: 
  - Instead of mapping, you could use `Array.fill` intelligently with a new operation depending on the use case.

- **Typed arrays** (if performance is critical and objects can be avoided):
  - Using typed arrays (like `Uint8Array`) could also be a consideration if performance needs outweigh the demand for objects.
  
### Conclusion:
Different methods for creating and populating arrays exhibit varying performance characteristics. This benchmarking test provides valuable insights into how each approach handles performance and memory usage in different situations. Software engineers should consider their specific use cases and the potential trade-offs between readability, maintainability, and execution speed when choosing an array creation strategy.

Related benchmarks:

compare the ways to generate an array filled with empty objects for iteration 2 (version: 1)

- Array.push - Array.apply: Array.apply(null, Array(100)) - Destructuring operator: [...Array(100)] - Array.prototype.fill Array(100).fill(undefined) - Array.from Array.from({ length: 100 })

Comparing performance of: Array.apply(null, Array(n)) vs [...Array(n)] vs Array(n).fill(null) vs Array.from({ length: n }) vs Array.from({ length:n }, (item, i) => i) vs Array.push vs Array with length + push vs new Array.fill(null)

Created: 2 months ago by: Guest

Jump to the latest result

Array.apply(null, Array(n))

[...Array(n)]

Array(n).fill(null)

Array.from({ length: n })

Array.from({ length:n }, (item, i) => i)

Array.push

Array with length + push

new Array.fill(null)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):