Benchmark: parse date - MeasureThat.net

Script Preparation code:

var REGEX = /(\d{4})-(\d{2})-(\d{2})(T(\d{2}):(\d{2})(:(\d{2}))?)?/;

function withRegex(str) {
	var match = str.match(REGEX);
	if (match) {
    	return new Date(match[1], match[2], match[3], match[5], match[6], match[8]);
    }
	return null;
}

function withSubstr(str) {
  var year = parseInt(str.substr(0, 4), 10),
			month = parseInt(str.substr(5, 2), 10) - 1,
			day = parseInt(str.substr(8, 2), 10),
			hour = 0, minute = 0, second = 0;

		if (str.indexOf('T') > -1) {
			hour = parseInt(str.substr(11, 2), 10),
			minute = parseInt(str.substr(14, 2), 10),
			second = parseInt(str.substr(17, 2), 10);
		}

		return new Date(year, month, day, hour, minute, second);
}

Tests:

Regex
for (var i=0; i<100; ++i) { withRegex('1991-11-26T12:00:00'); withRegex('1991-11-26'); }
Substr
for (var i=0; i<100; ++i) { withSubstr('1991-11-26T12:00:00'); withSubstr('1991-11-26'); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Regex
Substr

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

I'll break down the provided JSON and explain what's being tested, the options compared, pros and cons of each approach, and other considerations.

**Benchmark Definition**

The benchmark definition is a JavaScript function that creates two regular expression (REGEX) patterns: `withRegex` and `withSubstr`. The purpose of these functions is to parse dates in the format "YYYY-MM-DDTHH:MM:SS" or "YYYY-MM-DD".

The `withRegex` function uses a REGEX pattern to match the date string. It returns a new Date object if the match is found.

The `withSubstr` function uses substring manipulation to extract the year, month, day, hour, minute, and second from the date string. It also handles cases where the date includes a time component ("T").

**Options Compared**

Two options are compared:

1. **Regex**: Using regular expressions to parse dates.
2. **Substr**: Using substring manipulation to parse dates.

**Pros and Cons of Each Approach**

**Regex:**

Pros:

* More accurate, as it can handle different date formats and edge cases.
* Can be more efficient for large datasets, as it's optimized for searching patterns in strings.

Cons:

* May be slower due to the overhead of regular expression parsing and matching.
* Requires a good understanding of REGEX syntax and patterns.

**Substr:**

Pros:

* Often faster, as substring manipulation is typically more efficient than regular expression parsing.
* Simpler to implement, as it only requires basic string operations.

Cons:

* May not be as accurate, as it relies on manual extraction of date components, which can lead to errors.
* Less flexible, as it's limited to a specific date format.

**Other Considerations**

Both approaches have their trade-offs. If accuracy and flexibility are crucial, the REGEX approach might be preferred. However, if speed and simplicity are more important, the Substr approach could be sufficient.

**Libraries Used**

None explicitly mentioned in the benchmark definition, but some libraries may be used implicitly or through dependencies. For example, Chrome 54's JavaScript engine likely includes built-in support for regular expressions.

**Special JS Features/Syntax**

None explicitly mentioned or required in this benchmark. However, it's essential to note that some modern JavaScript features and syntax might impact performance or functionality, such as:

* ES6+ features (e.g., arrow functions, template literals)
* async/await
* Promises

These features can affect the execution speed and accuracy of the benchmark results.

**Alternatives**

Other alternatives for parsing dates in JavaScript include:

1. **Date.parse()**: A built-in function that attempts to parse a string into a Date object.
2. **Moment.js**: A popular library for working with dates and times in JavaScript.
3. **Day.js**: Another popular library for working with dates and times in JavaScript.

These alternatives can offer different trade-offs in terms of accuracy, speed, and flexibility compared to the REGEX and Substr approaches used in this benchmark.

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.59 Safari/537.36

Browser/OS: Chrome 54 on Linux

View result in a separate tab

Test name	Executions per second
Regex	6683.7 Ops/sec
Substr	3400.3 Ops/sec

Related benchmarks:

parse date (version: 0)

Comparing performance of: Regex vs Substr

Created: 7 years ago by: Guest

Jump to the latest result

Regex

Substr

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):