Benchmark: new.target vs variable

Script Preparation code:

class variable {
constructor(){
this.a= this instanceof variable
}
}
class newTarget {
constructor(){
this.a= this instanceof new.target
}
}

Tests:

variable
for(let i = 3000; --i;) new variable
new.target
for(let i = 3000; --i;) new newTarget

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
variable
new.target

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 131 on Android

View result in a separate tab

Test name	Executions per second
variable	39010.0 Ops/sec
new.target	64482.4 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON is designed to compare the performance of two different ways of instantiating objects in JavaScript: using a standard class instantiation (with the `new` keyword), and using the `new.target` meta-property.

### Benchmark Definition and Preparation

- **Classes**: Two classes are defined for the benchmark:
  1. **`variable`**: This class is instantiated directly using the `new` operator.
  2. **`newTarget`**: This class makes use of the `new.target` meta-property, which is a special feature in JavaScript that can be used inside the constructor to determine how the current function was called. It offers a way to determine if a function or constructor was invoked with `new` or not.

**Purpose of `new.target`**: 
- The `new.target` meta-property is useful because it determines if the constructor was called directly with `new` or if it was called in a different context (like a regular function call which would throw an error). It aids in writing constructors that behave differently based on how they are called.

### Test Cases

Two test cases are defined to execute benchmarks for each of the classes:

1. **`variable`**:
   - **Benchmark Definition**: `for(let i = 3000; --i;) new variable`
   - This executes the constructor of the `variable` class 3000 times in a loop.

2. **`newTarget`**:
   - **Benchmark Definition**: `for(let i = 3000; --i;) new newTarget`
   - This executes the constructor of the `newTarget` class 3000 times in a loop as well.

### Results Interpretation

From the benchmark results provided:
- **`newTarget` executed with an average rate of ~1599.19 executions per second.**
- **`variable` executed with an average rate of ~1508.12 executions per second.**

It shows that instantiating an object using the `new.target` mechanism is slightly more performant than the traditional class instantiation in this specific test.

### Pros and Cons

- **Pros of Using `new.target`**:
  1. It allows for more robust constructor designs, ensuring the constructor's intended usage context is adhered to.
  2. It can facilitate cleaner coding patterns by encapsulating the instantiation logic within the class.
  
- **Cons of Using `new.target`**:
  1. It's a more recent addition to JavaScript (introduced in ES2015), which may lead to compatibility issues with older JavaScript environments that do not support it.
  2. If not carefully designed, misuse of `new.target` could complicate constructors leading to performance or maintainability issues.

### Other Considerations

- **Performance Variability**: Results may vary based on the JavaScript engine, as optimizations could be different in various environments (like V8 in Chrome vs. SpiderMonkey in Firefox).
- **Alternatives**: Other alternatives include using function constructor patterns, factory functions, or object literal syntax for creating instances. Each comes with its own set of benefits and drawbacks like setup time, maintainability, readability, and potential performance impacts.

Overall, this benchmark illustrates how two different instantiation approaches can be compared not only in terms of performance but also in how they can influence the design of JavaScript applications.

Related benchmarks:

new.target vs variable (version: 1)

Comparing performance of: variable vs new.target

Created: one year ago by: Guest

Jump to the latest result

variable

new.target

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):