Benchmark: map vs reverse for vs for vs push vs unshift

Script Preparation code:

var arr = new Array(500).fill().map(()=>({id:Math.random()**Math.random()**Math.random()}));

Tests:

map
const res1=arr.map(({id})=>id>Math.random()?{foo:'bar'}:{bar:'foo'});
reverse for
const res2=new Array(arr.length); for (let i=arr.length-1;i>-1;i--){ res2[i]=arr[i].id>Math.random()?{foo:'bar'}:{bar:'foo'} }
for
const res2=new Array(arr.length); for (let i=0;i<arr.length;i++){ res2[i]=arr[i].id>Math.random()?{foo:'bar'}:{bar:'foo'} }
for push
const res2=[] for (let i=0;i<arr.length;i++){ res2.push(arr[i].id>Math.random()?{foo:'bar'}:{bar:'foo'}) }
reverse for unshift
const res2=new Array(); for (let i=arr.length-1;i>-1;i--){ res2.unshift(arr[i].id>Math.random()?{foo:'bar'}:{bar:'foo'}) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
reverse for
for
for push
reverse for unshift

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36 Edg/128.0.0.0

Browser/OS: Chrome 128 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
map	37545.5 Ops/sec
reverse for	25309.4 Ops/sec
for	19245.6 Ops/sec
for push	19035.5 Ops/sec
reverse for unshift	19034.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Definition**

The benchmark is designed to compare the performance of four different approaches: `map()`, `for` loop, `push()` array method, and `unshift()` array method on an array of 500 objects. The benchmark is repeated for each approach, allowing users to compare their relative performance.

**Options Compared**

1. **Map()**: Uses the `Array.prototype.map()` method to create a new array with transformed elements.
2. **For loop**: Uses a traditional `for` loop to iterate over the array and apply transformations.
3. **Push()**: Uses the `Array.prototype.push()` method to add transformed elements to the end of the original array.
4. **Unshift()**: Uses the `Array.prototype.unshift()` method to add transformed elements to the beginning of the original array.

**Pros and Cons of Each Approach**

1. **Map()**:
	* Pros: Efficient, concise, and easy to read. Creates a new array with transformed elements.
	* Cons: Can be slower than other approaches due to the creation of a new array.
2. **For loop**:
	* Pros: Fast, flexible, and allows for manual control over iteration.
	* Cons: Can be verbose and error-prone if not implemented correctly.
3. **Push()**:
	* Pros: Simple, efficient, and modifies the original array.
	* Cons: Can lead to slower performance due to the repeated push operations.
4. **Unshift()**:
	* Pros: Fast, flexible, and allows for manual control over iteration.
	* Cons: Can be less readable than other approaches due to the use of `unshift()`.

**Other Considerations**

1. **Array creation**: Creating a new array can be expensive in terms of memory allocation and garbage collection. The `map()` method creates a new array, while the other approaches modify the original array.
2. **Iteration order**: The iteration order of the `for` loop can lead to unexpected results if not controlled carefully.

**Library/Dependencies**

None mentioned in the benchmark definition.

**Special JS Features/Syntax**

1. **Rest parameter syntax (`{foo:'bar'}`)**: Used to create objects with rest parameters.
2. **Conditional operator (`? :`)**: Used for conditional expressions, such as `id>Math.random()?{foo:'bar'}:{bar:'foo'}`.

**Alternatives**

Other approaches to compare in the benchmark could include:

1. **Reduce()**: Uses a callback function to iterate over an array and accumulate a value.
2. **forEach()**: Calls a provided function once for each element in an array.
3. **Sliced arrays**: Creating sliced copies of the original array for transformation.

These alternatives would allow users to explore different optimization strategies and gain insights into the performance characteristics of various JavaScript approaches.

Related benchmarks:

map vs reverse for vs for vs push vs unshift (version: 0)

Comparing performance of: map vs reverse for vs for vs for push vs reverse for unshift

Created: 4 months ago by: Guest

Jump to the latest result

map

reverse for

for

for push

reverse for unshift

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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