Benchmark: epoch milliseconds to ISO string

Script Preparation code:

var seed = Date.now();

function toISO1(x) {
    Number.isFinite(x);

    const time = new Date(x);
    
    const year = String(time.getUTCFullYear()).padStart(2, '0');
    const mo = String(time.getUTCMonth()+1).padStart(2, '0');
    const da = String(time.getUTCDate()).padStart(2, '0');
    const ho = String(time.getUTCHours()).padStart(2, '0');
    const mi = String(time.getUTCMinutes()).padStart(2, '0');
    const se = String(time.getUTCSeconds()).padStart(2, '0');
    const mil = String(time.getUTCMilliseconds()).padStart(3, '0');
    
    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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I'll break down the provided benchmark definition, test cases, and latest benchmark results.

**Benchmark Definition**
The benchmark definition is a JSON object that describes two functions: `toISO1` and `toISO2`. Both functions are supposed to convert an epoch time into an ISO string. However, their implementation differs.

**Function `toISO1`**

This function takes an epoch time as input and returns an ISO string in the format "YYYY-MM-DDTHH:mm:ss.sssZ". Here's what it does:

1. It checks if the input is a finite number using `Number.isFinite(x)`.
2. It creates a new `Date` object from the epoch time.
3. It extracts the year, month, day, hour, minute, second, and millisecond from the date object.
4. It pads each value with leading zeros to ensure two digits.
5. It returns the formatted ISO string.

**Function `toISO2`**

This function takes an epoch time as input and returns an ISO string using the `toISOString()` method of the `Date` object. This is a more concise way to achieve the same result as `toISO1`.

**Options Compared**
The two functions are compared for performance:

* **`toISO1`**: uses manual date parsing and formatting.
* **`toISO2`**: uses the `toISOString()` method of the `Date` object, which is a built-in function.

**Pros and Cons**

**`toISO1`**:
Pros:

* More control over the output format.
* May be more suitable for specific use cases where manual formatting is required.

Cons:

* More verbose code.
* Requires manual date parsing, which can be error-prone.

**`toISO2`**:
Pros:

* Concise and readable code.
* Uses a built-in function, making it more efficient and less prone to errors.

Cons:

* Less control over the output format.
* May not be suitable for specific use cases where manual formatting is required.

**Library**
Neither of these functions uses an external library. However, `Date` objects are part of the JavaScript standard library.

**Special JS Feature or Syntax**
There are no special JavaScript features or syntax used in this benchmark.

**Benchmark Preparation Code**
The preparation code is provided as a script that initializes a seed value using `Date.now()`. This ensures that the tests start with a consistent starting point.

**Other Alternatives**

If you wanted to implement an alternative to these functions, you could consider using:

* **`Intl.DateTimeFormat`**: a more modern and flexible way to format dates and times.
* **`moment.js`**: a popular library for date and time manipulation.
* **`date-fns`**: another popular library for date and time manipulation.

However, keep in mind that these alternatives may introduce additional dependencies and complexity.

Related benchmarks:

epoch milliseconds to ISO string (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):