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

Historical Performance Data aggregated from 51 community runs

Desktop Results:

Chrome 45 runs

string type

21.3M/s

instanceof

9.8M/s

property

8.8M/s

string type + undefined

8.6M/s

Fastest: string type (2.5x faster)

View exact numbers

✓ string type: 21,266,100 ops/sec
• instanceof: 9,830,011 ops/sec
• property: 8,758,757 ops/sec
• string type + undefined: 8,618,235 ops/sec

Firefox 6 runs

string type

1352.1M/s

string type + undefined

1323.8M/s

property

1292.8M/s

instanceof

168.5M/s

Fastest: string type (8.0x faster)

View exact numbers

✓ string type: 1,352,126,080 ops/sec
• string type + undefined: 1,323,798,016 ops/sec
• property: 1,292,818,048 ops/sec
• instanceof: 168,513,024 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

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

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36 Edg/137.0.0.0

Browser/OS: Chrome 137 on Windows

View result in a separate tab

string type + undefined

151.2M/s

property

148.0M/s

instanceof

144.0M/s

string type

135.3M/s

View exact numbers

Test name	Executions per second
✓ string type + undefined	151,225,232 Ops/sec
property	147,963,712 Ops/sec
instanceof	144,025,936 Ops/sec
string type	135,276,976 Ops/sec

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

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: 5 years ago by: Guest

Go to the latest result

instanceof

string type

string type + undefined

property

Historical Performance Data aggregated from 51 community runs

Desktop Results:

Chrome 45 runs

Firefox 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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: 5 years ago by: Guest

Go to the latest result

instanceof

string type

string type + undefined

property

Historical Performance Data aggregated from 51 community runs

Desktop Results:

Chrome 45 runs

Firefox 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

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