Benchmark: Should you cache Intl.DateTimeFormat?

Script Preparation code:

FORMAT = { day: '2-digit', month: 'short', year: 'numeric' }
cache = new Map()

Tests:

No caching
const date = new Intl.DateTimeFormat('en-AU', FORMAT).format(new Date())
With JSON-keyed cache
const key = JSON.stringify(FORMAT) let formatter = cache.get(key) if (!formatter) { formatter = new Intl.DateTimeFormat('en-AU', FORMAT) cache.set(key, formatter) } const date = formatter.format(new Date())

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
No caching
With JSON-keyed cache

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
No caching	39791.9 Ops/sec
With JSON-keyed cache	1561063.1 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 7 months ago):

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided JSON benchmark.

**What is being tested?**

The benchmark tests two approaches to create and use `Intl.DateTimeFormat` objects in JavaScript:

1. **Creating a new object each time**: In this approach, a new `Intl.DateTimeFormat` object is created every time it's needed, without any caching.
2. **Caching the formatted object using a JSON-stringified options object**: In this approach, the formatting options are serialized to a JSON string and stored in a cache (in this case, a `Map`). If the same format is needed again, the cached value is retrieved and reused.

**Options comparison**

In the first approach, no options are compared or optimized. The same `Intl.DateTimeFormat` object is created every time it's needed, which can lead to performance issues due to repeated creation of objects and potential memory leaks.

In the second approach, the formatting options (in this case, a set of day, month, and year formats) are compared and cached using a JSON string. This allows for faster creation of `Intl.DateTimeFormat` objects, as only one object needs to be created initially, and subsequent requests can use the cached value.

**Pros and Cons**

Approach 1 (no caching):

* Pros: Simple to implement and understand.
* Cons:
	+ Creates multiple `Intl.DateTimeFormat` objects, leading to performance issues and potential memory leaks.
	+ Lacks optimization for repeated formatting requests.

Approach 2 (caching using JSON-keyed cache):

* Pros:
	+ Reuses cached values, reducing the number of objects created and improving performance.
	+ Optimizes repeated formatting requests by reusing existing `Intl.DateTimeFormat` objects.
* Cons:
	+ Requires additional memory to store the cache.
	+ May lead to complexity if not implemented carefully.

**Library and purpose**

The `Intl.DateTimeFormat` library is part of the ECMAScript Internationalization API. Its purpose is to provide a way to format dates and numbers according to the rules of specific locales. The `Intl.DateTimeFormat` object allows you to specify formatting options, such as day, month, and year formats, which are then applied to date objects.

**Special JS feature or syntax**

The benchmark uses the `JSON.stringify()` function to serialize the formatting options into a JSON string, which is used as the cache key. This is a JavaScript feature that converts a value (in this case, an object) to a string format that can be stored and compared efficiently.

**Other alternatives**

Alternative approaches to caching `Intl.DateTimeFormat` objects could include:

1. Using a `WeakMap` instead of a `Map` for caching, which would allow the cache to automatically remove stale values.
2. Implementing a more sophisticated caching strategy, such as LRU (Least Recently Used) or a custom cache expiration policy.
3. Avoiding caching altogether and creating a new `Intl.DateTimeFormat` object every time it's needed.

However, these alternatives may introduce additional complexity and performance trade-offs, making the simple caching approach using a JSON-keyed cache a viable option for many use cases.

Related benchmarks:

Should you cache Intl.DateTimeFormat? (version: 0)

Testing creating a new Intl.DateTimeFormat each time vs. caching it using JSON-stringified options object as the key.

Comparing performance of: No caching vs With JSON-keyed cache

Created: one year ago by: Guest

Jump to the latest result

No caching

With JSON-keyed cache

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 7 months ago):