Benchmark: creating maps vs creating objects

Tests:

creating maps
for (let i = 0; i < 1000; ++i) { const map = new Map() map.set(i + "", i) }
creating objects
for (let i = 0; i < 1000; ++i) { const obj = {} obj[i + ""] = i }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
creating maps
creating objects

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 128 on Android

View result in a separate tab

Test name	Executions per second
creating maps	2702.9 Ops/sec
creating objects	423.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what is being tested in this benchmark.

**Benchmark Definition:**
The benchmark compares two approaches to create JavaScript objects:

1. **Creating Maps**: The script creates a new Map instance and sets an entry with the key as a string concatenation of `i` and `"}`, where `i` is an integer from 0 to 999.
2. **Creating Objects**: The script creates an empty object `{}` and sets a property with the key as a string concatenation of `i` and `"}`, where `i` is an integer from 0 to 999.

**Options Compared:**
The benchmark compares the performance of these two approaches:

* Creating Maps (using JavaScript's built-in Map data structure)
* Creating Objects (using plain JavaScript objects)

**Pros and Cons of Each Approach:**

* **Creating Maps**: This approach uses a hash table, which provides fast lookups, insertions, and deletions. However, it may have a higher memory overhead due to the use of an object with specific keys.
* **Creating Objects**: This approach creates a plain JavaScript object, which can be less efficient for large datasets since objects are inherently slower than hash tables. However, it can be more flexible and easier to work with.

**Considerations:**

* The benchmark measures the execution speed, which is likely influenced by factors such as caching, memoization, or other performance optimization techniques.
* The script concatenates strings using `" + "` for string interpolation, which may lead to slower performance compared to modern JavaScript's template literals (`${expression}`).

**Library or Built-in Feature Used:**
None of the benchmark uses any external libraries. It only relies on built-in JavaScript features.

**Special JS Feature or Syntax:**
The benchmark uses string concatenation using `" + "` for string interpolation, which is a relatively old syntax in modern JavaScript. While it's still supported for compatibility reasons, more recent versions of JavaScript might use template literals (`${expression}`) instead.

**Other Alternatives:**

If you want to explore alternative approaches or optimize the existing ones, here are some additional options:

* Using `Object.assign()` to create objects could be another approach.
* Creating arrays with the same properties as the Map and then iterating over it might provide similar performance.
* Utilizing modern JavaScript's `Map.prototype.set()` methods for better cache locality.

Keep in mind that these alternatives may require modifications to your benchmark script, which is outside the scope of this explanation.

Related benchmarks:

creating maps vs creating objects (version: 0)

Comparing performance of: creating maps vs creating objects

Created: one year ago by: Registered User

Jump to the latest result

creating maps

creating objects

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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