Benchmark: Test array concat with larger array

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Script Preparation code:

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async function globalMeasureThatScriptPrepareFunction() {
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}

Tests:

copy
var getConcatenation = function(nums) { let ans = []; for (i = 0; i < nums.length; i++) { ans[i] = nums[i]; ans[i + nums.length] = nums[i]; } return ans; }; let largeArray = Array.from({ length: 10_000_000 }, (_, i) => i); getConcatenation(largeArray);
concat
var getConcatenation = function (nums) { return nums.concat(nums); }; let largeArray = Array.from({ length: 10_000_000 }, (_, i) => i); getConcatenation(largeArray);
in place
var getConcatenation = function(nums) { const len = nums.length; for (i = 0; i < len; i++) { nums[i + len] = nums[i]; } return nums; }; let largeArray = Array.from({ length: 10_000_000 }, (_, i) => i); getConcatenation(largeArray);
Spread operator
/** * @param {number[]} nums * @return {number[]} */ var getConcatenation = function (nums) { return [...nums, ...nums]; }; let largeArray = Array.from({ length: 10_000_000 }, (_, i) => i); getConcatenation(largeArray);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
copy
concat
in place
Spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
copy	1.1 Ops/sec
concat	3.3 Ops/sec
in place	1.8 Ops/sec
Spread operator	2.3 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark focuses on comparing three different approaches for concatenating a large array (specifically, an array containing 10 million integers) in JavaScript. Each test method represents a distinct approach to achieve the same goal: creating a new array that consists of two copies of the original array.

### Test Cases Overview

1. **Copy Approach**:
   ```javascript
   var getConcatenation = function(nums) {
       let ans = [];
       for (i = 0; i < nums.length; i++) {
           ans[i] = nums[i];
           ans[i + nums.length] = nums[i];
       }  
       return ans;
   };
   ```
   - **Description**: This approach creates a new array `ans`. It iterates over each element of the input array `nums`, copying the elements first to `ans` and then appending the same elements again from the original array.
   - **Pros**: The code is straightforward and easy to understand; it explicitly shows how elements are copied.
   - **Cons**: It has the overhead of managing a new array and explicit indexing, which could lead to performance degradation with larger datasets.

2. **Concat Approach**:
   ```javascript
   var getConcatenation = function (nums) {
       return nums.concat(nums);
   };
   ```
   - **Description**: This approach utilizes the built-in `concat` method of the array. It simply calls `nums.concat(nums)` which technically duplicates the entire array.
   - **Pros**: The `concat` method is concise and optimized within JavaScript’s engine, potentially executing faster than manual copying operations.
   - **Cons**: The implementation might be less clear regarding what happens under the hood, and the internal optimizations may vary between different JavaScript engines.

3. **In-Place Approach**:
   ```javascript
   var getConcatenation = function(nums) {
       const len = nums.length;
       for (i = 0; i < len; i++) {
           nums[i + len] = nums[i];
       }  
       return nums;
   };
   ```
   - **Description**: This method modifies the original array in-place. It directly writes a copy of itself to the second half of the same array, effectively doubling its size.
   - **Pros**: This method is memory efficient as it doesn't require the creation of a separate array, thus saving on memory allocation overhead.
   - **Cons**: It modifies the original array, which may not always be desirable. It can also lead to complications if the array is expected to remain unchanged in subsequent operations.

### Benchmark Results
The benchmark results illustrate the performance of these three methods in terms of "Executions Per Second":

- **Concat Method**: ~3.29 executions/sec (fastest)
- **In-Place Method**: ~1.75 executions/sec (middle performance)
- **Copy Method**: ~1.00 executions/sec (slowest)

### Other Considerations
- **Memory Management**: The copy and in-place methods may face issues with large arrays, especially in terms of memory allocation. The in-place method tends to be more efficient in memory usage, but at the cost of data integrity during execution.
- **Use Cases**: The choice between these methods may depend on specific use cases. For example, if you need to retain the original array unchanged, the `concat` method may be preferable despite its slower execution time.
- **Readability vs Performance**: While performance is crucial, code maintainability and clarity should also be factored into the decision of which method to use. The `concat` method is more readable, which may be a significant factor in collaborative environments.

### Alternatives
- **Spread Operator**: The spread operator (`[...nums, ...nums]`) can also be used to concatenate arrays in a more modern and readable manner, though performance characteristics vary.
- **Array.prototype.push()**: Another method is to use the `push()` function in a loop to append elements manually.
- **Typed Arrays**: If dealing with numeric data, JavaScript's `TypedArray` could provide performance benefits in terms of speed and memory usage, especially in numerical computations.

In summary, the benchmark evaluates array concatenation techniques against a backdrop of performance, memory management, readability, and situational use cases, offering valuable insights for developers faced with similar challenges in their projects.

Related benchmarks:

Test array concat with larger array (version: 2)

Comparing performance of: copy vs concat vs in place vs Spread operator

Created: 4 days ago by: Registered User

Jump to the latest result

copy

concat

in place

Spread operator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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