Benchmark: function typeof benchmark

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

function do_not_optimize(v) { $._ = v; }
const $ = { _: null, __() { return console.log($._); } };

function A({x,y}) {
  do_not_optimize( x ? x : do_not_optimize(y));
}

function B({x}) {
  do_not_optimize(typeof x =="string" ? x : do_not_optimize(x));
}

Tests:

split typeof
let c = 1000; while (c--){ A({y: () => "hi"}) A({y:() => "hi"}) A({x:"hi"}) }
typeof
let c = 1000; while (c--){ B({x: () => "hi"}) B({x:() => "hi"}) B({x:"hi"}) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
split typeof
typeof

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; rv:141.0) Gecko/20100101 Firefox/141.0

Browser/OS: Firefox 141 on Windows

View result in a separate tab

Test name	Executions per second
split typeof	27157.4 Ops/sec
typeof	40835.6 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 10 months ago):

LLMs can make mistakes. Check important info.

In the provided benchmark setup, two JavaScript functions `A` and `B` are being tested for performance differences in how they handle input values, particularly concerning the `typeof` operator and conditional checks. Here’s an explanation of what each function tests, along with the performance differences and considerations.

### Overview of Benchmark Tests

1. **Function A: `split typeof`**
   - **Test Code**: 
     ```javascript
     A({y: () => "hi"});
     A({y: () => "hi"});
     A({x: "hi"});
     ```
   - **Functionality**: 
     `A` takes an object with properties `x` and `y`. If `x` is truthy, it simply returns `x`. If `x` is falsy, it calls `do_not_optimize` with `y`, which is a function that returns the string "hi".
   - **Purpose**: The test aims to assess how `A` handles the truthiness of the input and the performance of checking for a truthy value versus performing an operation on a fallback value.

2. **Function B: `typeof`**
   - **Test Code**: 
     ```javascript
     B({x: () => "hi"});
     B({x: () => "hi"});
     B({x: "hi"});
     ```
   - **Functionality**: 
     `B` checks the type of `x` to ascertain if it is a string. If `x` is a string, it returns it; if not, it performs the `do_not_optimize` on `x`. The focus here is specifically on the performance of the `typeof` operation compared to the simple truthiness check done in function A.
   - **Purpose**: To evaluate how the `typeof` operator affects performance when determining the nature of the input variable.

### Comparison of Approaches

#### Pros and Cons:

- **Function A (`split typeof`)**:
  - **Pros**:
    - Simpler logic with a direct truthiness check; can be faster in scenarios where the input is frequently a truthy value.
    - Suitable for cases where the data type of `x` is less important than the fact that it holds a value.
  - **Cons**:
    - May lead to unexpected behaviors if the input `x` is falsy (like `0`, `false`, `null`, etc.), which may not capture cases where type validation is necessary.

- **Function B (`typeof`)**:
  - **Pros**:
    - Provides explicit type checking with `typeof`, allowing better control over the function's behavior based on data types.
    - Useful when the validation of data type matters significantly (e.g., debugging, ensuring code correctness).
  - **Cons**:
    - May introduce overhead due to additional type checking, which can slow down performance in high-frequency calls compared to simpler checks.

### Additional Considerations

- **Performance Measurement**: The test results indicate how many executions per second each function achieved. `split typeof` achieved approximately 50,717 executions per second, while the `typeof` variant managed around 49,372. The clear distinction in performance reflects the cost of type checking compared to evaluating truthy values.

- **Alternatives**: Other methods to check types could involve using `instanceof` for objects or leveraging stricter types with tools like TypeScript to avoid runtime type checks altogether. Additionally, if validation for multiple types becomes complex, implementing a library (e.g., Yup or Joi) for schema validation can be an option, albeit with additional overhead in setup and execution time.

In conclusion, the choice between these two approaches should be informed by the specific requirements of the application—whether type safety or performance is the primary concern. Each method has its trade-offs, and understanding their implications helps in making informed decisions in JavaScript performance optimization.

Related benchmarks:

function typeof benchmark (version: 1)

Comparing performance of: split typeof vs typeof

Created: 10 months ago by: Guest

Jump to the latest result

split typeof

typeof

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 10 months ago):