Benchmark: InstanceOf vs String type

HTML Preparation code:

<script>
class TestClass {
    constructor() {
        this.a = 2;
        this.t = 'mesh';
    }
}
</script>

Script Preparation code:

var obj = new TestClass();

Tests:

instanceof
obj instanceof TestClass;
string type
obj.t === 'mesh'
string type + undefined
obj.t !== undefined
property
obj.a !== undefined

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
string type
string type + undefined
property

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the Benchmark Definition JSON and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to measure the performance of different approaches in JavaScript for comparing types or properties of an object. The test compares three scenarios:

1. Using the `instanceof` operator
2. Comparing a basic string type using equality (`===`)
3. Comparing a string type with `undefined`

**Script Preparation Code**

The script preparation code creates an instance of a custom class `TestClass`, which has two properties: `a` (an integer) and `t` (a string).

```javascript
var obj = new TestClass();
```

**Html Preparation Code**

The HTML preparation code includes the definition of the `TestClass` class.

```html
<script>
    class TestClass {
        constructor() {
            this.a = 2;
            this.t = 'mesh';
        }
    }
</script>
```

Now, let's break down each individual test case:

**Test Case 1: `instanceof` Operator**

The benchmark definition uses the `instanceof` operator to check if the object `obj` is an instance of the `TestClass` class.

```javascript
"obj instanceof TestClass;"
```

**Pros and Cons**

* **Pros**: The `instanceof` operator can be more efficient than equality checks for certain use cases, especially when dealing with complex objects or large datasets.
* **Cons**: In this specific benchmark, the `instanceof` operator may not always perform better than equality checks.

**Test Case 2: Comparing a basic string type**

The benchmark definition uses equality (`===`) to compare the value of the `t` property with a literal string `'mesh'`.

```javascript
"obj.t === 'mesh'"
```

**Pros and Cons**

* **Pros**: Equality checks are simple and straightforward, making them easy to understand and maintain.
* **Cons**: This approach can be slower than using `instanceof` or other specialized methods when dealing with large datasets or complex objects.

**Test Case 3: Comparing a string type with `undefined`**

The benchmark definition uses equality (`===`) to compare the value of the `t` property with `undefined`.

```javascript
"obj.t !== undefined"
```

This test case is likely included to highlight potential pitfalls in equality checks when dealing with objects that may have `undefined` values.

**Test Case 4: Comparing a property**

The benchmark definition uses equality (`!==`) to compare the value of the `a` property with `undefined`.

```javascript
"obj.a !== undefined"
```

This test case is likely included to demonstrate the importance of properly checking for the presence of properties when dealing with objects that may not always have them.

**Libraries and Special JS Features**

In this benchmark, no specific libraries or features are used. The focus is on comparing basic types and properties using built-in JavaScript operators.

However, if you're interested in exploring other alternatives, here are some options:

* **Other Equality Operators**: Besides `===` and `!==`, there's also the `===` with a loose comparison (e.g., `obj.t === undefined`) and the `!=='` operator for case-insensitive string comparisons.
* **Type Checking Libraries**: If you need more advanced type checking capabilities, you may want to consider libraries like TypeScript or TypeScript-inspired tools like Flow.

Keep in mind that these alternatives might not be relevant to this specific benchmark, but they can be useful in other scenarios.

Latest run results:

Run details: (Test run date: 5 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36 Edg/130.0.0.0

Browser/OS: Chrome 130 on Windows

View result in a separate tab

Test name	Executions per second
instanceof	4392082.5 Ops/sec
string type	5692376.0 Ops/sec
string type + undefined	4111585.8 Ops/sec
property	4337211.5 Ops/sec

Related benchmarks:

InstanceOf vs String type (version: 0)

Measure the performance of instanceOf operator vs comparing a basic string type.

Comparing performance of: instanceof vs string type vs string type + undefined vs property

Created: 3 years ago by: Guest

Jump to the latest result

instanceof

string type

string type + undefined

property

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):