Benchmark: eval vs new Function (Sample JS Functions)

Script Preparation code:

var newFunc = new Function("let r = Math.random().toString(36).substring(7).includes('x');");

Tests:

eval
eval("let r = Math.random().toString(36).substring(7).includes('x');");
new Function
newFunc();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
eval
new Function

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36 Edg/138.0.0.0

Browser/OS: Chrome 138 on Windows

View result in a separate tab

Test name	Executions per second
eval	4607927.5 Ops/sec
new Function	6408443.0 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 explain what's being tested.

**Benchmark Overview**

The benchmark is comparing two approaches: `eval` and `new Function`. The goal is to measure which approach is faster, more efficient, or has better performance characteristics.

**Options Compared**

Two options are being compared:

1. **`eval`**: A built-in JavaScript function that evaluates a string as JavaScript code.
2. **`new Function`**: A constructor function used to create a new function object. The syntax `new Function("code")` creates a new function with the specified code.

**Pros and Cons of Each Approach**

1. **`eval`**:
	* Pros: Can be convenient for evaluating simple expressions or executing strings as JavaScript code.
	* Cons: Can be slow, as it involves parsing and compiling the code string, which can lead to performance issues with complex or large code snippets. Additionally, `eval` can also introduce security risks if used with untrusted input.
2. **`new Function`**:
	* Pros: Provides more control over the creation of function objects, allowing for better optimization and caching. It's generally considered a safer option than `eval`, as it avoids the risk of executing arbitrary code.
	* Cons: Requires specifying the full function syntax, which can be cumbersome for simple expressions.

**Library Usage**

In this benchmark, the `Function` constructor is used to create a new function object. This is a built-in JavaScript library, and its purpose is to provide a way to dynamically create function objects from strings or other data sources.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes being used in these test cases. The benchmark focuses on the performance comparison between `eval` and `new Function`.

**Other Alternatives**

If you're interested in exploring alternative approaches for executing code, here are a few options:

1. **`Function.prototype.toString()`**: This method returns a string representation of the function, which can be used to create a new function object.
2. **`bind()` or `call()` methods**: These methods allow you to invoke functions with specific arguments and contexts.

However, these alternatives are not being compared in this benchmark.

**Benchmark Preparation Code**

The preparation code for each test case is provided:

* For the `eval` test case: `let r = Math.random().toString(36).substring(7).includes('x');`
* For the `new Function` test case: `var newFunc = new Function("let r = Math.random().toString(36).substring(7).includes('x');");`

These code snippets are used to define a simple expression that tests the performance of each approach.

**Latest Benchmark Result**

The latest benchmark results show:

* For the `new Function` test case: 438,8521.5 executions per second
* For the `eval` test case: 178,9463.375 executions per second

These results suggest that `new Function` is significantly faster than `eval` in this specific benchmark scenario.

I hope this explanation helps you understand what's being tested in this benchmark!

Related benchmarks:

eval vs new Function (Sample JS Functions) (version: 0)

Comparing performance of: eval vs new Function

Created: 7 years ago by: Guest

Jump to the latest result

eval

new Function

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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