Benchmark: native reverse find vs native array findLast vs for loop find

HTML Preparation code:

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.core.js"></script>
<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Script Preparation code:

var users = [
  { 'user': 'joey',  'age': 32 },
  { 'user': 'ross',    'age': 41 },
  { 'user': 'joey',  'age': 32 },
  { 'user': 'ross',    'age': 41 },
  { 'user': 'joey',  'age': 32 },
  { 'user': 'ross',    'age': 41 },
  { 'user': 'joey',  'age': 32 },
  { 'user': 'ross',    'age': 41 },
  { 'user': 'chandler', 'age': 39 }
]

Tests:

array find
// Native users.slice().reverse().find(function (o) { return o.age < 40; })
array findlast
users.slice().findLast(function (o) { return o.age < 40; })
for loop
let lastItem = undefined; for (let i = users.length - 1; i >= 0; i--) { if (users[i].age < 40) { lastItem = users[i]; break; // Exit the loop once the item is found } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array find
array findlast
for loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 19 days ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:148.0) Gecko/20100101 Firefox/148.0

Browser/OS: Firefox 148 on Linux

View result in a separate tab

Test name	Executions per second
array find	21133500.0 Ops/sec
array findlast	28614752.0 Ops/sec
for loop	1063910464.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided benchmark measures the performance of three different approaches to find an element in an array with specific conditions: using `array.find()`, `array.findLast()`, and a manual `for` loop.

**Test Cases**

There are three test cases:

1. **array find**: Uses `slice()` to create a copy of the original array, reverses it, and then finds the first element that satisfies the condition (`o.age < 40`) using the `find()` method.
2. **array findlast**: Uses `slice()` to create a copy of the original array, finds the last element that satisfies the condition (`o.age < 40`) using the `findLast()` method.
3. **for loop**: Iterates over the array in reverse order and checks each element's age until it finds one that is less than 40.

**Options Compared**

The benchmark compares the performance of:

* Using `array.find()` (Test Case 1)
* Using `array.findLast()` (Test Case 2)
* A manual `for` loop (Test Case 3)

**Pros and Cons of Each Approach**

1. **array find**:
	* Pros: Simple, readable, and easy to implement.
	* Cons: Creates a copy of the array, which can be memory-intensive for large datasets.
2. **array findlast**:
	* Pros: More efficient than `find()` since it only returns the last element that satisfies the condition, rather than searching the entire array.
	* Cons: May not work correctly if the array is empty or contains multiple elements with the same condition (in this case, no such issues).
3. **for loop**:
	* Pros: Highly customizable and can be optimized for specific use cases.
	* Cons: More verbose, error-prone, and may require additional memory to store variables.

**Libraries Used**

The benchmark uses two JavaScript libraries:

1. **Lodash**: The `find()` and `findLast()` methods are part of Lodash's utility functions. Lodash is a popular utility library that provides a wide range of functions for tasks like array manipulation, functional programming, and more.
2. **No additional libraries** are used in the manual `for` loop implementation.

**Special JavaScript Features/Syntax**

The benchmark uses the following special JavaScript features:

1. **Spread operator (`...`)**: Used in the `slice()` method to create a copy of the original array.
2. **Arrow functions**: Used in the `find()` and `findLast()` methods to define small, anonymous functions.

**Alternatives**

Other approaches to find an element in an array with specific conditions might include:

* Using `filter()`: Instead of finding a single element, you can use `filter()` to create a new array with all elements that satisfy the condition.
* Using a custom implementation with a separate function for each iteration: This approach would require manual memory management and may be more error-prone than using built-in methods like `find()` or `for` loops.

Keep in mind that the choice of approach depends on the specific requirements and constraints of your use case.

Related benchmarks:

native reverse find vs native array findLast vs for loop find (version: 0)

Compare the new ES6 spread operator with the traditional concat() method

Comparing performance of: array find vs array findlast vs for loop

Created: one year ago by: Guest

Jump to the latest result

array find

array findlast

for loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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