Benchmark: epoch milliseconds to ISO string, precalculated numbers

Script Preparation code:

var seed = Date.now();

var twoDigits = [];

for(let i = 0; i<100; i++) {
	twoDigits.push(String(i).padStart(2, '0'));
}

var threeDigits = [];

for(let i = 0; i<1000; i++) {
	threeDigits.push(String(i).padStart(3, '0'));
}

function toISO1(x) {
    Number.isFinite(x);

    const time = new Date(x);
    
    const year = String(time.getUTCFullYear());
    const mo = twoDigits[time.getUTCMonth()+1];
    const da = twoDigits[time.getUTCDate()];
    const ho = twoDigits[time.getUTCHours()];
    const mi = twoDigits[time.getUTCMinutes()];
    const se = twoDigits[time.getUTCSeconds()];
    const mil = threeDigits[time.getUTCMilliseconds()];
    
    return `${year}-${mo}-${da}T${ho}:${mi}:${se}.${mil}Z`;
}

function toISO2(x) {
	return new Date(x).toISOString();
}

Tests:

template strings and padding
var value = toISO1(seed);
toISOString()
var value = toISO2(seed);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
template strings and padding
toISOString()

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 break down the provided benchmark definition, test cases, and latest results.

**Benchmark Definition**

The benchmark defines two functions: `toISO1` and `toISO2`, which convert an epoch time to an ISO string. The main difference between these two functions is how they construct the ISO string.

`toISO1` uses a template string with explicit formatting, while `toISO2` uses the built-in `toISOString()` method of the `Date` object.

**Options Compared**

The benchmark compares the performance of:

* Using template strings for string formatting (`toISO1`)
* Using the `toISOString()` method of the `Date` object (`toISO2`)

**Pros and Cons of Each Approach:**

1. **Template Strings (toISO1)**:
	* Pros:
		+ More control over the output format
		+ Can be useful for complex formatting scenarios
	* Cons:
		+ May be slower due to string manipulation and concatenation
2. **toISOString() method (toISO2)**:
	* Pros:
		+ Faster, as it's a built-in method optimized for performance
		+ Reduces the need for manual string formatting
	* Cons:
		+ Less control over the output format
		+ May not be suitable for complex formatting scenarios

**Library and Its Purpose**

In this benchmark, there is no explicitly mentioned library. However, `Date` objects are used extensively in both functions.

The `Date` object is a built-in JavaScript object that provides a way to represent dates and times. In this context, it's used to parse epoch time and generate ISO strings.

**Special JS Features or Syntax**

There is no special JS feature or syntax being tested here, apart from the use of template literals (in `toISO1`) which was introduced in ECMAScript 2015.

However, it's worth noting that the `toISOString()` method has been part of the JavaScript language since ECMAScript 2009, so it predates modern features like template literals.

**Alternatives**

Other alternatives for converting epoch time to an ISO string include:

* Using a dedicated library like Moment.js or Luxon
* Implementing a custom parsing logic using regular expressions or numerical calculations
* Utilizing cloud-based services that offer timestamp-to-ISO conversions (e.g., AWS API Gateway with the CloudWatch service)

Keep in mind that these alternatives might not be optimized for performance, and may require more development effort to implement correctly.

Related benchmarks:

epoch milliseconds to ISO string, precalculated numbers (version: 0)

A function that converts an epoch time into an ISO string

Comparing performance of: template strings and padding vs toISOString()

Created: 5 years ago by: Guest

Jump to the latest result

template strings and padding

toISOString()

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):