Benchmark: typeof vs type in var

Script Preparation code:

var foo = function() {}

Tests:

var
var type = typeof foo; type === 'string'; type === 'object'; type === 'function';
typeof
typeof foo === 'string'; typeof foo === 'object'; typeof foo === 'function';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
var
typeof

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**
The benchmark is defined by two script preparation codes, which are executed to prepare the test environment:

1. `var foo = function() {}`
2. An empty string (`null`).

These scripts are used as variables in the benchmark tests.

**Individual Test Cases**

There are two test cases:

### var
```javascript
var type = typeof foo;
type === 'string';
type === 'object';
type === 'function';
```

In this test, the `typeof` operator is applied to the variable `foo`, which contains an empty function expression. The expected outcomes are:

1. `type` should be `'object'` (because functions are objects in JavaScript)
2. `type` should not be `'string'`
3. `type` should not be `'function'`

### typeof
```javascript
typeof foo === 'string';
typeoffoo foo === 'object';
typeoffoo foo === 'function';
```

In this test, the `typeof` operator is called directly on the variable `foo`. The expected outcomes are:

1. `foo` should be a string literal (which it's not)
2. `typeof foo` should not be `'object'`
3. `typeof foo` should not be `'function'`

**Options Compared**
The two approaches being compared are:

* Using the `var` keyword to declare variables and then applying the `typeof` operator
* Calling the `typeof` operator directly on variables

**Pros and Cons**

* **Using `var`**: This approach is more verbose, but it's a more explicit way of declaring variables. It also allows for better error handling and debugging.
* **Calling `typeof` directly**: This approach is concise and easier to read, but it can lead to unexpected behavior if the variable hasn't been declared with `var`, `let`, or `const`.

**Library**
None

No libraries are being used in this benchmark.

**Special JS Feature/Syntax**
The benchmark uses a feature of JavaScript called "variable shadowing". This occurs when a variable with the same name is declared within a scope, potentially hiding variables from outer scopes. In this case, the `foo` variable is declared twice: once as an empty function expression and again as a string literal.

**Other Alternatives**
If you wanted to write similar benchmarks, you could consider using:

* Jest or Mocha for benchmarking
* A testing framework like Cypress or Playwright for testing web applications
* The ` performance.now()` method for measuring execution time in JavaScript

Keep in mind that the specific details of this benchmark (e.g., how it's set up and executed) may not be immediately clear to everyone, so it's essential to consider the context and requirements when writing similar benchmarks.

Latest run results:

Run details: (Test run date: 2025 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36

Browser/OS: Chrome 63 on Windows

View result in a separate tab

Test name	Executions per second
var	11324224.0 Ops/sec
typeof	3801330.5 Ops/sec

Related benchmarks:

typeof vs type in var (version: 0)

Comparing performance of: var vs typeof

Created: 6 years ago by: Guest

Jump to the latest result

var

typeof

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):