Benchmark: Date toString vs. valueOf

Script Preparation code:

var dates = [];
for (var i = 0; i < 1000000; i++)
  dates.push(new Date(+(new Date(1970, 0, 1)) + (i * 1000 * 60 * 60 * 24)));

Tests:

Date toString
dates.map(d => d.toString())
Date.valueOf()
dates.map(d => d.valueOf())
Date+
dates.map(d => +d)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Date toString
Date.valueOf()
Date+

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark test cases and explain what's being tested, compared, and their pros and cons.

**Benchmark Definition JSON**

The benchmark definition is a JSON object that contains the following information:

* `Name`: A human-readable name for the benchmark.
* `Description`: An optional description of the benchmark (not used in this case).
* `Script Preparation Code`: A JavaScript code snippet that prepares the test environment. In this case, it creates an array of 1 million dates using the `Date` constructor.
* `Html Preparation Code`: An optional HTML code snippet that prepares the HTML environment (not used in this case).

**Individual Test Cases**

There are three test cases:

1. **"Date toString"`**
	* **Benchmark Definition**: `dates.map(d => d.toString())`
	* This benchmark measures the time it takes to convert an array of dates to a string using the `toString()` method.
2. **"Date.valueOf()"**
	* **Benchmark Definition**: `dates.map(d => d.valueOf())`
	* This benchmark measures the time it takes to convert an array of dates to their numeric values using the `valueOf()` method.
3. **"Date+"**
	* **Benchmark Definition**: `dates.map(d => +d)`
	* This benchmark measures the time it takes to directly convert an array of dates to numbers using the unary plus operator (`+`).

**Comparison**

These three benchmarks compare the performance of different approaches to work with dates in JavaScript:

1. Using `toString()` method
2. Using `valueOf()` method
3. Directly converting to numbers using the unary plus operator (`+`)

**Pros and Cons**

Here's a brief analysis of each approach:

1. **Using `toString()` method**:
	* Pros: Simple, widely supported, and works in most browsers.
	* Cons: Can be slow for large datasets due to the overhead of string conversion.
2. **Using `valueOf()` method**:
	* Pros: Fast and efficient, as it doesn't require string conversion.
	* Cons: May not work correctly with non-NaN dates or dates with fractional seconds.
3. **Directly converting to numbers using (`+`)**:
	* Pros: Fast and efficient, as it avoids the overhead of string conversion.
	* Cons: May not work correctly with non-numeric dates (e.g., NaN) or dates with fractional seconds.

**Library Usage**

There is no explicit library usage in this benchmark. However, if a library like Lodash or Moment.js were used, they might provide utility functions for working with dates that could affect the benchmark results.

**Special JS Features/Syntax**

None of the benchmarks explicitly use special JavaScript features or syntax beyond the standard `Date` constructor and the unary plus operator (`+`). However, if the `valueOf()` method was used to convert a date to its fractional second component (e.g., `d.valueOf() + d.getMilliseconds()`), it would require the use of the `getMilliseconds()` method, which is not explicitly mentioned in the benchmark.

**Other Alternatives**

If you need to measure performance for other date-related operations, consider exploring benchmarks like:

* Converting dates to ISO strings (e.g., `new Date().toISOString()`)
* Parsing dates from strings (e.g., `Date.parse("2022-01-01T00:00:00.000Z")`)
* Using the Intl.DateTimeFormat API for date formatting

Keep in mind that these alternatives may not be included in the MeasureThat.net benchmarking framework, but they can provide valuable insights into specific use cases.

I hope this explanation helps you understand what's being tested and compared in the provided benchmark!

Related benchmarks:

Date toString vs. valueOf (version: 0)

Comparing performance of: Date toString vs Date.valueOf() vs Date+

Created: 6 years ago by: Guest

Jump to the latest result

Date toString

Date.valueOf()

Date+

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):