Benchmark: Array.includes vs. Dictionary lookup

Script Preparation code:

var a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
var b = {0: 0, 1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9};
var randomIndex = Math.floor(Math.random() * 10);

Tests:

Array.includes
a.includes(randomIndex);
Dictionary lookup
b[randomIndex];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.includes
Dictionary lookup

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Definition**

The benchmark definition provided represents two test cases: `Array.includes` and `Dictionary lookup`. The script preparation code creates an array `a` and a dictionary-like object `b` with the same elements. A random index is generated using `Math.random()`, which will be used to access either the `Array.includes()` method or the dictionary.

**Options Compared**

Two options are being compared:

1. **Array.includes()**: This method checks if a given value (in this case, the randomly generated index) exists in the array.
2. **Dictionary lookup**: This approach uses direct key-value lookups to access the value associated with the random index in the dictionary.

**Pros and Cons**

**Array.includes():**

Pros:

* Wide browser support: `includes()` is a standard method in modern JavaScript engines, ensuring compatibility across various browsers.
* Simple implementation: The `includes()` method only requires a single element check, making it efficient in terms of computation.

Cons:

* Potential performance overhead due to the iteration over the array's elements. This might lead to slower execution times for large arrays.

**Dictionary lookup:**

Pros:

* Direct access: Using direct key-value lookups can be faster than iterating over an array, as the browser doesn't need to search for the index.
* Reduced memory allocation: Since we're using a dictionary-like object, there's less memory overhead compared to creating and manipulating an array.

Cons:

* Browser support limitations: The `Dictionary lookup` approach might not work in older browsers or those that don't support object property access with square brackets (`[]`).
* Additional computation: We need to perform the key-value lookup using the random index, which could introduce additional computational overhead.

**Library**

In this benchmark, the `Array.prototype.includes()` method is being used. This is a standard JavaScript method implemented in modern browsers and Node.js engines, making it widely supported.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax used in this benchmark that require specific knowledge to understand.

**Other Alternatives**

For comparison purposes, other alternatives could include:

* Using `indexOf()` instead of `includes()`: This method performs a linear search for the specified value within the array.
* Utilizing `Array.prototype.indexOf()` directly: This is an alternative way to achieve direct access to an element's index in an array.
* Implementing a custom binary search algorithm: For larger arrays, a more efficient data structure like a balanced binary search tree or a skip list could be used.

Keep in mind that each of these alternatives may have their own set of trade-offs and performance implications.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.113 Safari/537.36

Browser/OS: Chrome 81 on Mac OS X 10.15.4

View result in a separate tab

Test name	Executions per second
Array.includes	5236625.0 Ops/sec
Dictionary lookup	6347432.0 Ops/sec

Related benchmarks:

Array.includes vs. Dictionary lookup (version: 0)

Comparing performance of: Array.includes vs Dictionary lookup

Created: 4 years ago by: Guest

Jump to the latest result

Array.includes

Dictionary lookup

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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