Benchmark: test 111111 - MeasureThat.net

Script Preparation code:

var obj = {};
for(i=0; i<1000; i++){obj[i+" item"]=true;};

Tests:

in
var a = ("999 item" in obj);
hasownproperty
var a = obj.hasOwnProperty("999 item");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
in
hasownproperty

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

I'll explain the JavaScript microbenchmark on MeasureThat.net.

**Overview**

The benchmark measures how fast two approaches are to check if an object property exists: using the `in` operator and using the `hasOwnProperty` method.

**Approaches Compared**

1. **Using the `in` operator**: This approach checks if a property with the given key exists in the object by using the `in` keyword.
2. **Using `hasOwnProperty`**: This approach uses the `hasOwnProperty` method, which returns true if the object has the specified property as its own property (i.e., not inherited from its prototype).

**Pros and Cons**

* **Using the `in` operator**:
	+ Pros: simple and fast.
	+ Cons: may return false positives if the property is inherited through the prototype chain.
* **Using `hasOwnProperty`**:
	+ Pros: returns only own properties, avoiding potential false positives.
	+ Cons: slightly slower than using `in`.

The `hasOwnProperty` approach is generally considered better because it avoids potential false positives and provides a more accurate result. However, in some cases, the difference might be negligible.

**Library and Special JS Features**

There are no libraries or special JavaScript features mentioned in this benchmark. The focus is solely on comparing two basic approaches to checking if an object property exists.

**Other Considerations**

Another approach not considered in this benchmark is using `in` with a string literal that includes the property name, like `"999 item" in obj`. While this might seem similar to using `hasOwnProperty`, it's actually slower and less accurate because it performs a case-sensitive search.

If you wanted to include this approach in your benchmark, you could use the following script:
```javascript
var a = (999 item in obj);
```
Keep in mind that this approach is not recommended due to its potential false positives and slower performance.

**Alternatives**

Some alternatives to these approaches exist:

1. **Using `in` with a property access**: Instead of just checking if the property exists, you can use it as part of an expression.
```javascript
var a = obj[999 item];
```
This approach is faster than using `hasOwnProperty` but still returns only own properties.

2. **Using `Object.hasOwn` (ECMAScript 2020+)**: If your target browser supports ECMAScript 2020+, you can use the new `Object.hasOwn` method, which provides a more modern and accurate way to check if an object has a property.
```javascript
var a = Object.hasOwn(obj, "999 item");
```
While this approach is not available in older browsers, it's worth considering for its improved accuracy and simplicity.

Related benchmarks:

test 111111 (version: 0)

Comparing performance of: in vs hasownproperty

Created: 6 years ago by: Guest

Jump to the latest result

in

hasownproperty

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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