Benchmark: new Map vs Spread

Script Preparation code:

var cpcodes = new Array(100000).fill(undefined).map((_,i) => `${i}`);

var selectionsMap = new Map([
  [ 'dateRange', [ 'custom' ] ],
  [ 'start', [ '2022-04-01T00:00:00Z' ] ],
  [ 'end', [ '2022-04-08T00:00:00Z' ] ],
  [ 'timezone', [ 'Europe/Warsaw' ] ],
  [ 'network', [ 'mobile' ] ],
  [ 'string_match_options', [ 'start_with' ] ],
  [ 'cpcodes', cpcodes ]
]);

var selectionsObject = {
  dateRange: [
    'custom'
  ],
  start: [
    '2022-04-01T00:00:00Z'
  ],
  end: [
    '2022-04-08T00:00:00Z'
  ],
  timezone: [
    'Europe/Warsaw'
  ],
  network: [
    'mobile'
  ],
  string_match_options: [
    'start_with'
  ],
  cpcodes: cpcodes
}

Tests:

spread
let a = { ...selectionsObject, network: [ 'non_mobile' ] };
new map
selectionsMap.set('network', [ 'non_mobile' ]); let a = new Map(selectionsMap);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
new map

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what is being tested.

**Benchmark Definition**

The provided benchmark definition represents two different approaches for creating an object `a` based on another object `selectionsObject`. The main difference between these approaches lies in how they handle the `network` property.

**Approach 1: Using Spread Operator (`"spread"`)**

In this approach, a new object `a` is created by spreading the `selectionsObject` and modifying the `network` property:
```javascript
let a = { ...selectionsObject, network: [ 'non_mobile' ] };
```
**Pros:**

* Easy to read and write
* Creates a new object with all properties from `selectionsObject`, including `network`

**Cons:**

* Can be slower due to the creation of a new object

**Approach 2: Using `Map` (`"new map"`)**

In this approach, a new `Map` is created using the `selectionsMap` object and then converted to an object:
```javascript
let a = new Map(selectionsMap).get('network');
```
However, according to the provided benchmark definition, the correct code should be:
```javascript
let a = new Map([['network', [ 'non_mobile' ]]]).get('network');
```

**Pros:**

* Can be faster due to the efficient use of `Map` data structure

**Cons:**

* Less intuitive and may require more boilerplate code

In general, using `Map` can be beneficial when you need to efficiently store and retrieve key-value pairs. However, in this specific case, creating a new object with the modified `network` property might be easier to read and write.

The benchmark is comparing the performance of these two approaches on different browsers and devices.

**Library Used**

There is no explicit library mentioned in the provided benchmark definition. The use of `Map` data structure is part of the ECMAScript standard, so it's not a custom library.

**Special JS Feature/Syntax**

None of the test cases explicitly uses any special JavaScript features or syntax. However, using `let a = { ...selectionsObject, network: [ 'non_mobile' ] };` might be considered a more modern JavaScript feature, as it uses object destructuring and spread operator.

**Other Alternatives**

If you're looking for alternative approaches to create an object with a modified `network` property, some possible options include:

* Using a library like Lodash or underscore.js, which provide functions for working with objects and arrays.
* Creating a new object using the `Object.assign()` method:
```javascript
let a = Object.assign({}, selectionsObject, { network: [ 'non_mobile' ] });
```
However, keep in mind that these alternatives might have different performance characteristics compared to the original approaches.

Related benchmarks:

new Map vs Spread (version: 0)

Comparing performance of: spread vs new map

Created: 3 years ago by: Guest

Jump to the latest result

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):