Benchmark: reduce + map filter

Script Preparation code:

var customers = [
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: true, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" },
      { active: false, name: "a", email: "b" }
  ];
  
  Array.prototype.filterMap = function(filter) {
     const r = [];
     const len = this.length;
     for(let i=0; i<len; i++) {
        const item = filter(this[i], i, this);
        if (item !== undefined) {
           r.push(item);
        }
     }
     return r;
  };

Tests:

reduce
var emails = customers.filter( (c) => c.active) .map( (c) => ({ name: c.name, email: c.email }));
map
var emails = customers.filterMap( (c) => c.active ? { name: c.name, email: c.email } : undefined);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
map

Fastest: N/A

Slowest: N/A

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Autogenerated LLM Summary (model gemma2:9b, generated one year ago):

LLMs can make mistakes. Check important info.

This benchmark tests the performance of two different approaches to filtering and mapping an array of customer objects in JavaScript:

**Option 1: `reduce`**

* **Benchmark Definition:**  
  ```javascript
  var emails = customers.filter( (c) => c.active)\r\n            .map( (c) => ({ name: c.name, email: c.email }));
  ```

This approach uses the `.filter()` method to select active customers and then the `.map()` method to transform each active customer object into a new object containing just the `name` and `email`.

**Option 2: `filterMap` (Custom Method)**

* **Benchmark Definition:**
  ```javascript
  var emails = customers.filterMap(\r\n   (c) => c.active ?\r\n      { name: c.name, email: c.email } :\r\n      undefined);
  ```

This approach utilizes a custom method called `filterMap` which combines the functionality of `.filter()` and `.map()` into a single step. It iterates through the array, applies the provided function to each element, and only pushes non-undefined results into a new array.

**Pros and Cons:**

* **`reduce` approach:**
    * **Pros:**  More widely known and understood, utilizes standard JavaScript methods.
    * **Cons:** Requires two separate method calls which can lead to slightly more overhead.

* **`filterMap` approach:**
    * **Pros:** Potentially more concise and efficient by combining filtering and mapping into one step.
    * **Cons:**  Less common, relies on a custom implementation that might not be as optimized as built-in methods.

**Other Considerations:**

* **Array Size:** The performance difference between the two approaches may become more noticeable with larger arrays.
* **Complexity of Transformation:** If the transformation logic within `.map()` is complex, it could outweigh the potential efficiency gains of `filterMap`.

**Alternatives:**

* **Functional Programming Libraries:** Libraries like Lodash or Ramda offer optimized versions of functions like `filter` and `map`, potentially improving performance further.
* **Destructuring Assignment:** If you're only interested in specific properties from the customer objects, destructuring assignment within `.filter` and `.map` can make the code more concise and readable.

Let me know if you have any more questions!

Related benchmarks:

reduce + map filter (version: 0)

Comparing performance of: reduce vs map

Created: 6 years ago by: Guest

Jump to the latest result

reduce

map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model gemma2:9b, generated one year ago):