Benchmark: parseFloat isNaN vs RegEx parseFloat

Script Preparation code:

var n = "-5";
var regex = /^-?\d+$/;

Tests:

parseFloat isNaN
var v = parseFloat(n); var a = isNaN(v) ? n : v;
RegEx parseFloat
var a = regex.test(n) ? parseFloat(n) : n;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
parseFloat isNaN
RegEx parseFloat

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 JSON benchmark definition and test cases.

**What is tested:**
The provided benchmark measures the performance of two approaches to parse a string containing a negative number:

1. `parseFloat isNaN`: This approach uses the built-in JavaScript function `isNaN()` to check if the result of `parseFloat()` is NaN (Not a Number). If it is, the original value is returned; otherwise, the parsed float is returned.
2. `RegEx parseFloat`: This approach uses a regular expression (`^(-)?\\d+$`) to parse the string.

**Options compared:**
The benchmark compares the performance of these two approaches on a single test case, where the input string is `" -5"`. The options being compared are:

* Using `isNaN()` to check for NaN
* Using a regular expression to parse the string

**Pros and cons of each approach:**

1. **`parseFloat isNaN`**:
	* Pros:
		+ Lightweight and simple implementation.
		+ Fast, as it only requires a single function call.
	* Cons:
		+ May be slower than the regex approach due to the overhead of `isNaN()`.
2. **`RegEx parseFloat`**:
	* Pros:
		+ Can handle more complex parsing scenarios, such as parsing negative numbers with optional whitespace.
		+ Often faster than the `isNaN()` approach, especially for larger inputs.
	* Cons:
		+ Requires a regular expression, which can be slower to parse due to the overhead of string manipulation and pattern matching.

**Library and purpose:**
The `parseFloat` function is a built-in JavaScript function that parses a string as a floating-point number. It returns NaN if the input string cannot be parsed as a float.

**Special JS feature or syntax:**
There are no special features or syntax in this benchmark, other than using regular expressions for parsing.

**Other alternatives:**
If you want to test alternative approaches, some options could include:

* Using `Number()` instead of `parseFloat` (this would add additional parsing logic).
* Implementing a custom parser using a finite state machine.
* Comparing the performance of different regex patterns or optimization techniques.

It's worth noting that measuring the performance of JavaScript benchmarks can be complex due to factors like browser-specific optimizations, caching effects, and platform dependencies. The provided benchmark results should be treated with caution and may require further analysis to determine their reliability.

Related benchmarks:

parseFloat isNaN vs RegEx parseFloat (version: 0)

Comparing performance of: parseFloat isNaN vs RegEx parseFloat

Created: 3 years ago by: Guest

Jump to the latest result

parseFloat isNaN

RegEx parseFloat

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):