Benchmark: _.isArray vs Array.isArray

HTML Preparation code:


<script src='https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js'></script>

Script Preparation code:

var a = []
for(var i=0; i<100; i++){
	a[i] = `val${i}`
}

Tests:

_
_.isArray(a);
nat
Array.isArray(a)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
_
nat

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:147.0) Gecko/20100101 Firefox/147.0

Browser/OS: Firefox 147 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
_	189359312.0 Ops/sec
nat	231086464.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the benchmark and explain what's being tested, compared options, pros and cons of those approaches, library usage, special JavaScript features or syntax, and other considerations.

**Benchmark Overview**

The benchmark tests two alternatives for checking if an array is an instance of the `Array` constructor:

1. `_` (the underscore function) from the Underscore.js library
2. `Array.isArray()` (a built-in JavaScript method)

**Script Preparation Code**

The script preparation code creates a large array `a` with 100 elements, each containing a string value `"val${i}"`, where `i` is an index.

```javascript
var a = [];
for (var i = 0; i < 100; i++) {
    a[i] = 'val' + i;
}
```

**Html Preparation Code**

The HTML preparation code includes a reference to the Underscore.js library, which provides the `_` function used in the benchmark.

```html
<script src='https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js'></script>
```

**Test Cases**

There are two test cases:

1. `_.isArray(a);`
2. `Array.isArray(a);`

Both test cases create an array `a` and pass it to the respective function.

**Library Usage - Underscore.js**

Underscore.js is a popular JavaScript utility library that provides a concise way to perform common tasks, such as iterating over arrays or strings, creating functions, and more. The `_` function in this benchmark is used to check if an array is an instance of the `Array` constructor.

**Comparison Options**

The two options being compared are:

1. `_.isArray(a);`
2. `Array.isArray(a);`

**Pros and Cons of Each Approach:**

**_ (Underscore.js)**

Pros:

* Often faster than `Array.isArray()` because it can use native JavaScript methods under the hood.
* Can provide more flexible and concise way to perform array checks in certain scenarios.

Cons:

* Requires an additional library download (Underscore.js) and potential additional overhead due to its functionality.
* May not be as widely adopted or understood as the built-in `Array.isArray()` method.

**Array.isArray()**

Pros:

* Built into modern JavaScript engines, eliminating the need for a separate library.
* Widely supported and well-documented, making it easier to understand and use.
* Generally faster than using an external library like Underscore.js.

Cons:

* May not provide as concise or flexible way to perform array checks in certain scenarios.
* Can be slower than `_.isArray()` if optimized native methods are used under the hood.

**Other Considerations**

* The benchmark results show that Chrome 83, running on a Windows Desktop, favors `Array.isArray()`, while another instance runs faster with `_.isArray(a);`.
* These results may not generalize to other browsers, environments, or performance profiles.
* The choice between these two approaches ultimately depends on the specific requirements and constraints of your application.

**Alternatives**

If you don't want to use a third-party library like Underscore.js, you can implement an array check function similar to `Array.isArray()` using native JavaScript methods. For example:

```javascript
function isArray(arr) {
    return arr instanceof Array && arr.constructor === Array;
}
```

Alternatively, you could explore other libraries or implementations that provide alternative array check functions.

Keep in mind that the choice of implementation ultimately depends on your specific use case and performance requirements.

Related benchmarks:

_.isArray vs Array.isArray (version: 0)

a

Comparing performance of: _ vs nat

Created: 5 years ago by: Guest

Jump to the latest result

_

nat

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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