Benchmark: Map get VS Map has then get

Script Preparation code:

var i = 0, count = 1000, a;
var map = new Map();

for (i = 0; i < count; i++) {
  if (Math.random() > 0.5) {
    map.set(i, { val: 'a' });
  }
}

Tests:

Map 1
for (i = 0; i < count; i++) { let newVal = map.get(i); if (a) { a = newVal; } }
Map 2
for (i = 0; i < count; i++) { if (map.has(i)) { a = map.get(i).val; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map 1
Map 2

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36 Edg/135.0.0.0

Browser/OS: Chrome 135 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Map 1	21946.2 Ops/sec
Map 2	12510.5 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided JSON represents two individual test cases, each measuring the performance of JavaScript code that accesses and manipulates a Map data structure.

**Map vs. Map.has() vs. Map.get()**

In the benchmark definition, we have three different approaches to access and retrieve values from a Map:

1. **Simple `map.get(i)`**: This method retrieves the value associated with the key `i` directly.
2. **`map.has(i)` followed by `map.get(i).val`**: This approach first checks if the key `i` exists in the Map using `map.has(i)`, and then retrieves the value associated with that key using `map.get(i)`. Finally, it extracts the `val` property from the retrieved value.
3. **`if (a)` followed by `a = newVal`**: This approach uses a variable `a` to store the retrieved value. The code checks if `a` is truthy, and if so, assigns the new value (`newVal`) to `a`.

**Comparison of Approaches**

Here's a brief analysis of each approach:

* **Simple `map.get(i)`**: This is the most straightforward approach, as it directly retrieves the value associated with the key. However, it may not be suitable for all use cases, especially when working with large Maps or complex data structures.
* **`map.has(i)` followed by `map.get(i).val`**: This approach ensures that the key exists in the Map before attempting to retrieve its value. While it provides additional safety, it introduces an extra step and may incur a small performance overhead due to the repeated Map lookups.
* **`if (a)` followed by `a = newVal`**: This approach reuses the variable `a` to store the retrieved value, which can help reduce memory allocation and garbage collection overhead. However, if `a` is not initialized or reset before use, this approach may lead to unexpected behavior.

**Library: Lodash**

The benchmark uses the popular JavaScript library [Lodash](https://lodash.com/) for its `map.has()` method, which provides a convenient way to check if an object has a specific property. In this case, Lodash is used to ensure that the key `i` exists in the Map before attempting to retrieve its value.

**Special JS Feature: None**

There are no special JavaScript features or syntax used in this benchmark, making it accessible to developers with varying levels of familiarity with the language.

**Other Alternatives**

If you want to explore alternative approaches for accessing and manipulating Maps in JavaScript, consider the following options:

* Use the `Object.keys()` method to iterate over Map keys.
* Utilize the `Map.forEach()` method to iterate over Map entries.
* Employ a custom solution using recursion or loops to access and manipulate Map values.

Keep in mind that these alternatives may not provide the same level of performance or convenience as the original benchmark, but they can serve as an interesting exercise for developers looking to explore different approaches.

Related benchmarks:

Map get VS Map has then get (version: 0)

Map get VS Map has get

Comparing performance of: Map 1 vs Map 2

Created: 3 years ago by: Guest

Jump to the latest result

Map 1

Map 2

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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