Benchmark: indexOf vs push - MeasureThat.net

Tests:

filter index
let strArray = [ "q", "w", "w", "w", "e", "i", "u", "r"]; let findDuplicates = arr => arr.filter((item, index) => arr.indexOf(item) !== index); console.log(findDuplicates(strArray));
push
const strArray = [ "q", "w", "w", "e", "i", "u", "r", "q"]; const alreadySeen = {}; strArray.forEach(str => alreadySeen[str] ? console.log(str) : alreadySeen[str] = true);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter index
push

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 provided JSON data and explain what's being tested, compared, and discussed in the context of JavaScript microbenchmarks.

**What is being tested?**

MeasureThat.net is testing the performance of two different approaches to find duplicates in an array of strings:

1. **`filter()` method with `indexOf()`**: This approach uses the `filter()` method to create a new array with only the elements that are duplicates (i.e., `arr.indexOf(item) !== index`). The `indexOf()` method is used to check if an element exists in the array at a given index.
2. **Simple push-based approach**: This approach uses a simple loop to iterate over the array and keep track of seen strings using a hash object (`alreadySeen`).

**Options compared**

The two approaches are being compared to determine which one performs better in terms of execution speed.

**Pros and cons of each approach:**

1. **`filter()` method with `indexOf()`**:
	* Pros:
		+ Concise and readable code.
		+ Leverages the optimized implementation of `filter()` and `indexOf()` methods.
	* Cons:
		+ May have higher overhead due to the extra function call (`arr.indexOf(item)`).
		+ Can be slower if the array is large or if many elements are duplicates (since `indexOf()` needs to scan the entire array).
2. **Simple push-based approach**:
	* Pros:
		+ No additional function calls or overhead, making it potentially faster.
		+ Simple and easy to understand.
	* Cons:
		+ More verbose code compared to the first approach.

**Library usage**

Neither of the provided approaches uses any external libraries. However, if we were to extend this benchmark to include other methods for finding duplicates (e.g., `reduce()` or a custom implementation), we might consider using libraries like Lodash or Ramda, which provide optimized and concise implementations of these methods.

**Special JavaScript features/syntax**

Neither approach utilizes any special JavaScript features or syntax beyond standard ES6 features. However, if we were to modify the benchmark to include more advanced techniques (e.g., memoization or caching), we might need to consider using modern JavaScript features like `Symbol` or `WeakMap`.

**Other alternatives**

Some alternative approaches for finding duplicates in an array could include:

* Using a custom implementation with a hash table data structure.
* Utilizing the `Set` data structure, which is designed specifically for fast membership testing and set operations.
* Leveraging libraries like Lodash or Ramda, which provide optimized implementations of common algorithms.

Keep in mind that the choice of approach depends on the specific use case, performance requirements, and personal preference. The MeasureThat.net benchmark provides a useful comparison between two simple approaches, but more complex scenarios might require additional considerations and experimentation with different techniques.

Related benchmarks:

indexOf vs push (version: 0)

Comparing performance of: filter index vs push

Created: 3 years ago by: Guest

Jump to the latest result

filter index

push

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):