Benchmark: eval() vs new Function() - 2

Tests:

eval
eval("var str = '', i = 0; for(;i<1000;i++) { str += 'a';}");
new Function
Function("var str = '', i = 0; for(;i<1000;i++) { str += 'a';}")();
new Function2
Function("var str = '', i = 0; for(;i<1000;i++) { str += 'a';} return str;")();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
eval
new Function
new Function2

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.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition**

The benchmark measures the performance of `eval()` versus creating a new function using the `Function` constructor. The `eval()` function is used to execute a string as JavaScript code, while the `Function` constructor creates a new function from a given string.

**Options Compared**

Two options are compared:

1. **eval()**: This option uses the built-in `eval()` function to execute the provided string as JavaScript code.
2. **new Function()**: This option uses the `Function` constructor to create a new function from the provided string.

**Pros and Cons of Each Approach**

* **eval()**:
	+ Pros: Can be more concise and easier to write, especially for simple expressions or statements.
	+ Cons:
		- Performance overhead due to parsing and execution of the code.
		- Security risks if not used carefully (e.g., executing user-provided input).
* **new Function()**:
	+ Pros:
		- Better performance since it avoids the overhead of `eval()`.
		- More control over the creation of the function, including access to its properties and methods.
	+ Cons:
		- May be less concise than using `eval()` for simple expressions or statements.

**Library and Purpose**

The `Function` constructor is a built-in JavaScript object that creates a new function from a given string. It's used to dynamically create functions without requiring explicit function declarations.

In the provided benchmark, the `new Function` tests use the constructor with two slightly different syntaxes:

1. **new Function()**:
This is the simplest form of creating a new function using the `Function` constructor.
2. **new Function("...")()**:
This syntax creates a new function and immediately calls it (i.e., executes the function body).

**Special JS Feature or Syntax**

The benchmark doesn't use any special JavaScript features or syntax that would require additional explanation.

**Other Considerations**

* The benchmark is run in a desktop environment on Mac OS X 10.15.6, which might affect the results.
* The `RawUAString` field indicates the raw UA string sent by the browser to the server, but it's not directly relevant to the performance comparison.

**Alternatives**

Other alternatives for creating functions dynamically in JavaScript include:

1. **eval()**: As mentioned earlier, this is a more concise way to execute code, but with performance overhead.
2. **Function.prototype.toString()**: This method returns a string representation of the function, which can be used to create a new function using the `new` operator or other methods.

In conclusion, the benchmark measures the performance difference between using `eval()` versus creating a new function using the `Function` constructor. The results indicate that `new Function()` is more efficient than `eval()`.

Related benchmarks:

eval() vs new Function() - 2 (version: 0)

Comparing performance of: eval vs new Function vs new Function2

Created: 5 years ago by: Guest

Jump to the latest result

eval

new Function

new Function2

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):