Benchmark: Number vs + vs parseFloat + eval

Tests:

Number
var number = Number(Math.random().toFixed(2));
Unary +
var unary = +Math.random().toFixed(2);
parseFloat
var parse = parseFloat(Math.random().toFixed(2));
Eval
var eval1 = eval(Math.random().toFixed(2));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Number
Unary +
parseFloat
Eval

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Number	4474321.5 Ops/sec
Unary +	5782326.5 Ops/sec
parseFloat	4659840.5 Ops/sec
Eval	3218631.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its components.

**What is tested:**

The benchmark tests four different approaches to convert a string representation of a number from `Math.random().toFixed(2)`:

1. **Number**: Uses the built-in JavaScript function `Number()` to parse the string.
2. **Unary +**: Uses the unary `+` operator to convert the string.
3. **parseFloat**: Uses the `parseFloat()` function to parse the string.
4. **Eval**: Uses the `eval()` function to execute a script that converts the string.

**Options compared:**

The benchmark compares the performance of these four approaches:

*   **Number**: Directly uses the built-in JavaScript function to convert the string.
*   **Unary +**: Uses the unary `+` operator, which can be seen as equivalent to calling `Number()`, but is more efficient due to a historical reason (more on this later).
*   **parseFloat**: Uses a separate function to parse the string.
*   **Eval**: Uses a separate function to execute a script that converts the string.

**Pros and Cons:**

1.  **Number**:
    *   Pros: Directly uses the built-in JavaScript function, which is likely optimized for performance.
    *   Cons: May not be as efficient due to overhead of calling a function.
2.  **Unary +**: (Historical reason) The unary `+` operator was introduced in older versions of JavaScript and was meant to be more efficient than calling `Number()`. However, modern JavaScript engines have optimized the behavior of both approaches, making them comparable. This approach is still used for compatibility reasons or when direct function calls are not possible.
    *   Pros: More efficient due to reduced overhead compared to calling a separate function.
    *   Cons: May seem less efficient at first glance due to its historical context.
3.  **parseFloat**:
    *   Pros: Separates the parsing logic from the conversion, which might improve performance in certain scenarios.
    *   Cons: Requires an extra function call, which can add overhead.

4.  **Eval**: (Not recommended)
    *   Pros: None, as using `eval()` can be a security risk if not used carefully due to its ability to execute arbitrary JavaScript code.
    *   Cons: Significantly slower than the other approaches due to its dynamic nature and potential for malicious input.

**Library/Function:**

The benchmark uses several built-in JavaScript functions:

*   **Number()**: A built-in function that parses a string as a number.
*   **parseFloat()**: A built-in function that parses a string as a floating-point number.

These functions are optimized for performance and security, making them suitable choices in most cases.

**Special JS feature/Syntax:**

The benchmark does not require any special JavaScript features or syntax beyond what's required to run the tests. The use of `eval()` is generally discouraged due to potential security risks, but it's used here to illustrate its behavior in a controlled environment.

I hope this explanation helps! Let me know if you have further questions.

Related benchmarks:

Number vs + vs parseFloat + eval (version: 0)

Comparing performance of: Number vs Unary + vs parseFloat vs Eval

Created: 2 years ago by: Guest

Jump to the latest result

Number

Unary +

parseFloat

Eval

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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