Benchmark: null prototype hasProperty

Script Preparation code:

o = Object.create(null)
o.foo = 'bar'
o.baz = 'qux'

Tests:

using in
if ('bar' in o) return true;
using hasOwnProperty call
Object.prototype.hasOwnProperty.call(o, 'bar')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
using in
using hasOwnProperty call

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested, along with their pros and cons.

**Benchmark Definition**

The benchmark is testing two different ways to check if a property exists in an object. The test cases are:

1. `if ('bar' in o) return true;`
2. `Object.prototype.hasOwnProperty.call(o, 'bar')`

**What's being tested?**

Both approaches aim to determine whether the `o` object has a property called `'bar'`.

**Approach 1: Using `in` operator**

This approach uses the `in` operator to check if the property exists in the object. The syntax `if ('bar' in o)` checks if the string `'bar'` is present as a key in the object `o`. If it is, the code inside the `if` statement will execute.

**Pros:**

* Simple and concise
* Fast execution

**Cons:**

* Can be slower than other approaches because it has to iterate through the object's keys.
* Not all objects support the `in` operator, as some may have custom prototype chains that break its behavior.

**Approach 2: Using `hasOwnProperty.call()`**

This approach uses a static method from the `Object.prototype` to check if the property exists in the object. The syntax `Object.prototype.hasOwnProperty.call(o, 'bar')` checks if the object `o` has a property called `'bar'`. This method returns `true` if the property exists and `false` otherwise.

**Pros:**

* Fast execution
* Can be used with any object, regardless of its prototype chain

**Cons:**

* Less concise than the `in` operator approach
* May require additional imports or namespace resolution for older browsers

**Library and Purpose**

In this benchmark, no specific library is being tested. However, it's worth noting that both approaches use built-in JavaScript methods (`in` operator) or properties ( `hasOwnProperty.call()`).

**Special JS feature/Syntax**

There are no special JavaScript features or syntax used in these benchmarks.

Now, let's look at the benchmark result:

The results show two test cases with different execution times for each approach. The first test case uses the `in` operator and has a higher execution time (5380731.5 executions per second), while the second test case uses `hasOwnProperty.call()` and has a lower execution time (2790085.5 executions per second).

**Alternatives**

Other alternatives to check if a property exists in an object include:

* Using `Object.keys()`, which returns an array of keys for the object, and then checking if `'bar'` is present using `includes()`
* Using `Reflect.has()` or `hasOwnProperty()` (if available) methods
* Implementing custom checks using `for...in` loops

Keep in mind that each approach has its trade-offs, and the choice of which one to use depends on the specific requirements and constraints of your project.

Related benchmarks:

null prototype hasProperty (version: 0)

Comparing performance of: using in vs using hasOwnProperty call

Created: 4 years ago by: Registered User

Jump to the latest result

using in

using hasOwnProperty call

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):