Benchmark: test_spread_vs-map

Script Preparation code:

var data = new Array(100).fill(undefined).map((_,i) => i)
var obj = data.reduce((obj, idx) => {obj[idx] = idx; return obj}, {});
var map = new Map(Object.entries(obj));

Tests:

sp
let a = {...obj};
ma
let a = new Map(map);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
sp
ma

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's dive into the world of JavaScript microbenchmarks and analyze the provided benchmark.

**Benchmark Overview**

The test case, called `test_spread_vs_map`, is designed to compare the performance of two approaches: using the spread operator (`...`) to create a new object from an existing object (`obj`), versus creating a new Map from an existing Map (`map`). The benchmark aims to determine which approach is faster.

**Script Preparation Code**

The script preparation code creates an array `data` with 100 elements, each initialized to `undefined`. It then maps over this array to create a new array where each element is the index of the original array. This resulting array is used to create a new object (`obj`) where each property value is equal to its key value.

The code also creates a new Map (`map`) from an existing object (`obj`). The `Object.entries(obj)` expression returns an array of key-value pairs, which are then passed to the `Map` constructor to create a new map.

```javascript
var data = new Array(100).fill(undefined).map((_, i) => i)
var obj = data.reduce((obj, idx) => {obj[idx] = idx; return obj}, {})
var map = new Map(Object.entries(obj));
```

**Test Cases**

There are two test cases:

1. `sp` (short for "spread"): This test case uses the spread operator (`...`) to create a new object from the existing object (`obj`).
```javascript
let a = {...obj};
```
2. `ma` (short for "map"): This test case creates a new Map from the existing Map (`map`).
```javascript
let a = new Map(map);
```

**Library and Purpose**

In both test cases, a library is used: `Map`. A `Map` is a data structure that stores key-value pairs. In this benchmark, it's used to represent an object with indexed keys.

**Special JavaScript Feature or Syntax**

Neither of the test cases uses any special JavaScript features or syntax beyond the standard language.

**Pros and Cons**

Here are some pros and cons for each approach:

**Spread Operator (`...`)**

Pros:

* Simple to implement
* Can be used in a variety of contexts

Cons:

* May not perform as well as `Map` for large datasets, since it creates a new object with duplicate keys
* Can lead to performance issues if the resulting object is very large and has many duplicate keys

**Creating a New Map (`Map`)**

Pros:

* More efficient than creating an object with indexed keys, especially for large datasets
* Avoids potential issues with duplicate keys in objects

Cons:

* May be less intuitive or straightforward to use for some developers

**Other Alternatives**

If you wanted to compare the performance of these approaches, you might also consider using other methods, such as:

* Creating a new object using `Object.assign()` or `Object.create()`
* Using a library like Lodash's `cloneDeep()` function
* Implementing your own custom indexing mechanism

However, it's worth noting that the spread operator and creating a new Map are two distinct approaches that have different performance characteristics. The benchmark is likely designed to compare these two specific methods.

Overall, this benchmark provides a useful comparison of two common JavaScript patterns: using the spread operator to create an object with indexed keys versus creating a new Map from an existing Map.

Related benchmarks:

test_spread_vs-map (version: 0)

Comparing performance of: sp vs ma

Created: 2 years ago by: Guest

Jump to the latest result

sp

ma

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):