Benchmark: Object spread vs New map

Script Preparation code:

var data = new Array(100000).fill(undefined).map((_,i) => i)
var obj = data.reduce((obj, idx) => {obj[idx] = idx; return obj}, {});
var map = new Map(Object.entries(obj));

Tests:

Obj spread
let a = {...obj};
new Map
let a = new Map(map);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Obj spread
new Map

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 break down the benchmark and its results.

**Benchmark Overview**

The benchmark compares two approaches for creating an object from another data structure: object spread (using the `...` operator) and using a `Map`. The benchmark uses JavaScript as the programming language.

**Script Preparation Code**

The script preparation code is provided in the benchmark definition JSON:
```javascript
var data = new Array(100000).fill(undefined).map((_,i) => i)
var obj = data.reduce((obj, idx) => {obj[idx] = idx; return obj}, {})
var map = new Map(Object.entries(obj))
```
Here's what each line does:

1. Creates an array `data` of 100,000 elements, where each element is a unique number from 0 to 99,999.
2. Reduces the `data` array and creates an object `obj` with indices as property values.
3. Creates a new `Map` called `map` by iterating over the entries of `obj`.

**Test Cases**

The benchmark consists of two test cases:

1. **"Obj spread"**: This test case uses object spread to create an object from the `obj` variable:
```javascript
let a = {...obj};
```
This approach creates a shallow copy of the `obj` object by spreading its properties onto a new object.

2. **"new Map"**: This test case uses the `Map` constructor to create a map from the `map` variable:
```javascript
let a = new Map(map);
```
This approach creates an exact copy of the `map` data structure, including all its key-value pairs.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Object Spread:**
	+ Pros:
		- Easy to read and write
		- Fast and efficient for small objects
	+ Cons:
		- Can lead to shallow copies, losing some data (e.g., if the original object has a prototype chain)
		- Not suitable for large objects or complex data structures
* **new Map:**
	+ Pros:
		- Creates an exact copy of the map data structure, preserving all key-value pairs and properties
		- Suitable for large objects and complex data structures
	+ Cons:
		- More verbose than object spread
		- Can be slower for very small maps

**Library: None**

There is no external library used in this benchmark.

**Special JavaScript Features/Syntax: None**

No special JavaScript features or syntax are used beyond the standard `...` operator and `Map` constructor.

**Other Alternatives**

If you're looking for alternative approaches to object creation, consider:

* Using a library like Lodash's `cloneDeep()` function, which can create deep copies of objects.
* Using a library like Immutable.js, which provides a range of data structures and utilities for creating immutable data.
* Using native JavaScript methods like `JSON.parse(JSON.stringify(obj))`, but note that this can lead to slower performance and may not be suitable for large objects.

Keep in mind that the choice of approach depends on your specific use case, performance requirements, and personal preference.

Related benchmarks:

Object spread vs New map (version: 0)

Comparing performance of: Obj spread vs new Map

Created: 3 years ago by: Guest

Jump to the latest result

Obj spread

new Map

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):