Benchmark: indexOf vs foreEach

Tests:

map with indexOf
const arr = ["foo", "bar", "baz", "foo", "bar", "foo"]; let newArr = []; newArr= arr.map((word)=>{ return arr.indexOf(word) != arr.lastIndexOf(word) ? "" : word; });
foreach with map
const arr = ["foo", "bar", "baz", "foo", "bar", "foo"]; let newArr = []; let newObj = {}; arr.forEach((input, index) => { if (newObj[input]){ newObj[input] += 1; }else{ newObj[input] = 1; } }); newArr = arr.map((word)=>{ return newObj[word] > 1 ? "" : word; });
map doing nothing
const arr = ["foo", "bar", "baz", "foo", "bar", "foo"]; let newArr = []; newArr= arr.map((word)=>{ return word; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map with indexOf
foreach with map
map doing nothing

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 and explain what's being tested, compared, and its pros and cons.

**Benchmark Context**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The benchmark in question compares three approaches: `indexOf` with `map`, `forEach` with `map`, and simply using `map` without any additional logic.

**Test Cases**

There are three test cases:

1. **"map with indexOf"`**: This test case uses the `Array.prototype.indexOf()` method to check if an element appears multiple times in the array, and then uses the `Array.prototype.map()` method to create a new array based on this condition.
2. **"foreach with map"`**: This test case uses the `Array.prototype.forEach()` method to iterate over the elements of the array and update a counter object (`newObj`) based on the presence of each element. Then, it uses the `Array.prototype.map()` method to create a new array based on this counter.
3. **"map doing nothing"`**: This test case simply uses the `Array.prototype.map()` method without any additional logic.

**Comparison and Pros/Cons**

The three approaches are being compared in terms of their performance, specifically the number of executions per second.

Here's a brief summary of each approach:

* **"map with indexOf"`**: This approach is likely to be the fastest because it only uses `indexOf()` once for each element, which is an O(n) operation. However, since `indexOf()` can return -1 if the element is not found, this test case may incur some overhead due to unnecessary checks.
* **"foreach with map"`**: This approach is likely to be slower than the first one because it iterates over the elements twice: once using `forEach()` and once using `map()`. Additionally, creating a counter object (`newObj`) can also introduce additional overhead.
* **"map doing nothing"`**: This approach is likely to be the slowest because it simply uses `map()` without any additional logic. The overhead of calling `map()` on an empty array or with no elements may outweigh any potential benefits.

**Library Usage**

In this benchmark, there are no libraries explicitly mentioned, but it's worth noting that some modern JavaScript implementations, such as V8 (used by Chrome), have optimized implementations for certain methods like `indexOf()` and `forEach()`.

**Special JS Feature/Syntax**

There is one special feature used in this benchmark: the use of template literals (`\r\n` is not a literal syntax but in the code examples the backticks are). This feature allows for multi-line strings. All three test cases use template literals, so it's not specific to any particular approach.

**Other Alternatives**

If you want to implement these benchmarks yourself, here are some alternatives:

* Use a polyfill or a JavaScript runtime that provides optimized implementations of `indexOf()` and `forEach()`, such as V8.
* Write custom test harness using Node.js, Jest, or another testing framework.
* Implement the benchmark in a different programming language (e.g., C++, Java) if you want to compare performance with JavaScript.

Keep in mind that writing benchmarks can be complex and require careful consideration of factors like data distribution, hardware variability, and caching.

Related benchmarks:

indexOf vs foreEach (version: 2)

Comparing performance of: map with indexOf vs foreach with map vs map doing nothing

Created: 8 years ago by: Registered User

Jump to the latest result

map with indexOf

foreach with map

map doing nothing

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):