Benchmark: Array loop vs foreach vs map vs filter for update field in object

Script Preparation code:

   var arr = [];
   for (var i = 0; i < 1000; i++) {
       arr[i] = {
           'id': i
       };
   }

   function someFn(i) {
       return i * 3 * 8;
   }

Tests:

foreach
arr.forEach(function (item){ item.data = someFn(item.id); })
for
for (var i = 0, len = arr.length; i < len; i++) { arr[i].data = someFn(arr[i].id); }
map
arr.map(function(item){ item.data=someFn(item.id); });
filter
arr.filter(function(item){ item.data=someFn(item.id); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map
filter

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

The provided benchmark definition json represents a simple script that creates an array of objects with an `id` field and then applies a calculation to this data using four different approaches: `forEach`, `for`, `map`, and `filter`. The purpose of this benchmark is to compare the performance of these four methods in updating the `data` property of each object.

**Options being compared:**

1. **`forEach`**: This method iterates over an array, executing a provided function for each element.
2. **`for` loop**: A traditional loop that uses a variable to keep track of the iteration index.
3. **`map`**: This method creates a new array with the results of applying a provided function to each element in the original array.
4. **`filter`**: Similar to `map`, but it only includes elements for which the provided function returns true.

**Pros and cons of each approach:**

*   **`forEach`**:
    *   Pros: Easy to read, concise code, and can be used when iterating over an array.
    *   Cons: Can be slower than other methods due to the overhead of a separate loop or iterator.
*   **`for` loop**:
    *   Pros: Often faster than other methods since it uses a traditional loop.
    *   Cons: More verbose and requires manual indexing, which can increase errors.
*   **`map`**:
    *   Pros: Can be more efficient for large arrays since it avoids the overhead of multiple iterations (e.g., filtering).
    *   Cons: Creates a new array, which may not be desirable when memory is limited. Also, can be slower if the function being mapped is expensive.
*   **`filter`**:
    *   Pros: Similar to `map`, but only includes elements that pass the test.
    *   Cons: Can still be slow due to creating a new array and the overhead of filtering.

**Library usage:**

None of these methods use any external libraries. They are all built-in features of JavaScript.

**Special JS feature or syntax:**

The provided benchmark definition uses no special features or syntax beyond what's standard in JavaScript.

Now, let's look at some alternatives:

*   **Using a library**: There are libraries like Lodash that provide optimized versions of these methods for performance. However, MeasureThat.net is specifically interested in the built-in methods.
*   **Other approaches**: Other options could include using `reduce`, which combines multiple array operations into one; using `Promise.all` with `map` and `then` to handle updates sequentially; or even using a more functional programming approach like recursion.

Keep in mind that performance differences between these methods can vary depending on the specific use case, data size, and JavaScript environment.

Related benchmarks:

Array loop vs foreach vs map vs filter for update field in object (version: 0)

Comparing performance of: foreach vs for vs map vs filter

Created: 5 years ago by: Guest

Jump to the latest result

foreach

for

map

filter

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):