Benchmark: .map().flat() vs .flatMap()

Script Preparation code:

var arr = [];

for (let i = 0; i < 10000000; i++) {
    arr.push({nested: [i]});
}

Tests:

.map().flat()
arr.map((a) => a.nested).flat();
.flatMap()
arr.flatMap((a) => a.nested);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.map().flat()
.flatMap()

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 dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The benchmark definition represents a specific task or operation to be measured. In this case, we have two test cases:

1. `arr.map((a) => a.nested).flat()`: This line of code flattens an array of objects using the `map()` method and then applies the `flat()` method to flatten the result.
2. `arr.flatMap((a) => a.nested)`: This line of code also flattens an array of objects, but uses the `flatMap()` method instead of `map()` and `flat()`.

**Options Compared**

The two options are:

1. **Using `map()`, `flat()`, and chaining**: This approach involves using multiple methods to flatten the array.
2. **Using `flatMap()`**: This approach uses a single method, `flatMap()`, which flattens the array in one step.

**Pros and Cons of Each Approach**

1. **Chaining (`map()`, `flat()`)**:
	* Pros:
		+ Can be more intuitive for developers who are familiar with the individual methods.
		+ May allow for better optimization by allowing the browser's just-in-time (JIT) compiler to optimize each method individually.
	* Cons:
		+ Requires an additional step, which can increase overhead and potentially lead to slower performance.
		+ Can be less efficient due to the overhead of calling multiple methods.
2. **Using `flatMap()`**:
	* Pros:
		+ Simplifies the code and reduces the number of operations needed to flatten the array.
		+ Can be more efficient since it only requires a single method call, reducing overhead and potentially leading to faster performance.
	* Cons:
		+ May require additional development time for developers who are not familiar with `flatMap()`.
		+ May not provide as clear a mental model for the code's behavior.

**Library and Special JS Feature**

In this benchmark, there is no library used, but it does utilize JavaScript features that may be new or less common:

*   The use of arrow functions (`(a) => a.nested`) is a modern JavaScript feature introduced in ECMAScript 2015.
*   The `flatMap()` method was also introduced in ECMAScript 2019 and is supported by most modern browsers.

**Other Alternatives**

If the developers want to explore other options, they could consider:

1.  **Spreading arrays**: Instead of using methods like `map()`, `flat()`, or `flatMap()`, you can use array spreading (`[...arr.flat()]`) or a simple loop to achieve the same result.
2.  **Using libraries like Lodash or Ramda**: These libraries provide utility functions for common tasks, including array manipulation and flattening.
3.  **Native methods in specific browsers**: Some older versions of Internet Explorer, Safari, or Firefox do not support `flatMap()`, while newer versions may have their own native methods.

In conclusion, the choice between chaining (`map()`, `flat()`) and using `flatMap()` depends on your personal preference, development style, and target audience. The MeasureThat.net benchmark provides a helpful platform to explore these different approaches and compare performance in various browsers.

Related benchmarks:

.map().flat() vs .flatMap() (version: 0)

Comparing performance of: .map().flat() vs .flatMap()

Created: 3 years ago by: Guest

Jump to the latest result

.map().flat()

.flatMap()

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):