Benchmark: Concat Vs Spread [eungwang2]

Script Preparation code:

var firstArray = Array.from({length : 50000}, (v,i) => ({id : i, name : `firstArray${i}`}))
var secondArray = Array.from({length : 50000}, (v,i) => ({id : i, name : `secondArray${i}`}))

Tests:

concat
return firstArray.concat(secondArray);
spread
return [...firstArray,secondArray];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
concat
spread

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.

I'll break down the explanation into smaller parts to make it easier to understand.

**Benchmark Overview**

The MeasureThat.net benchmark measures the performance difference between two approaches: concatenating arrays using the `concat()` method and using the spread operator (`...`) to merge arrays. The test case, "Concat Vs Spread [eungwang2]," is used to compare these two approaches.

**Options Compared**

There are two options being compared:

1. **Concatenation using `concat()`:** This approach uses the `concat()` method to merge two arrays.
```javascript
var result = firstArray.concat(secondArray);
```
2. **Spread operator (`...`):** This approach uses the spread operator to merge two arrays.
```javascript
var result = [...firstArray, secondArray];
```

**Pros and Cons**

**Concatenation using `concat()`:**

Pros:

* Well-established method with good browser support.
* Easy to read and write.

Cons:

* Can lead to performance issues when dealing with large arrays or arrays that are not in a contiguous block of memory.
* Can cause issues with garbage collection, leading to slower performance.

**Spread operator (`...`):**

Pros:

* More modern and efficient approach.
* Does not create intermediate arrays, reducing the risk of performance issues.
* Can be faster than concatenation for large arrays or arrays that are not in a contiguous block of memory.

Cons:

* May not work as expected in older browsers or Internet Explorer (IE).
* Requires familiarity with the spread operator syntax.

**Other Considerations**

When using the spread operator, it's essential to note that it only works when both operands are arrays. If one operand is a non-array value, the result will be an array containing the original value and the spread operand as an array element.

**Library Used**

There is no library explicitly mentioned in this benchmark definition. However, the `Array.from()` method is used to create arrays with a specified length and initial values. This method is part of the JavaScript standard library.

**Special JS Feature or Syntax**

The benchmark uses the spread operator (`...`) syntax, which was introduced in ECMAScript 2015 (ES6). If your browser does not support ES6 features, you may encounter issues running this benchmark.

**Alternatives**

If you prefer a different approach to merging arrays, here are some alternatives:

* Using `Array.prototype.push()`: You can push elements from one array into another using the `push()` method. However, this approach is less efficient than concatenation or the spread operator.
* Using `Array.prototype.splice()`: Similar to `push()`, you can use `splice()` to add elements from one array to another. This approach is also less efficient than concatenation or the spread operator.

Here's an example of using `Array.prototype.push()`:
```javascript
var result = [];
firstArray.forEach((element) => {
  result.push(element);
});
result.push(...secondArray);
```
And here's an example of using `Array.prototype.splice()`:
```javascript
var result = [];
firstArray.forEach((element) => {
  result.push(element);
});
result.splice(result.length, 0, ...secondArray);
```

Related benchmarks:

Concat Vs Spread [eungwang2] (version: 0)

Comparing performance of: concat vs spread

Created: 3 years ago by: Guest

Jump to the latest result

concat

spread

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):