Benchmark: conditional self-assignment vs. membership check with in vs. membership check with hasOwnProperty vs. null check

Script Preparation code:

var x = {
    foo: []
};
var keys = Array.from({
    length: 5000
}).map((x, i) => i < 2500 ? i : i - 2500);

Tests:

hasOwnProperty membership check
for (const key of keys) { if (!Object.prototype.hasOwnProperty.call(x, key)) { x[key] = []; } }
self-assignment
for (const key of keys) { x[key] = x[key] ?? []; }
in membership check
for (const key of keys) { if (!(key in x)) { x[key] = []; } }
null check
for (const key of keys) { if (x[key] == null) { x[key] = []; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
hasOwnProperty membership check
self-assignment
in membership check
null check

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36

Browser/OS: Chrome 114 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
hasOwnProperty membership check	2069.3 Ops/sec
self-assignment	2920.5 Ops/sec
in membership check	6152.3 Ops/sec
null check	5753.1 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of what's being tested in this benchmark.

**Benchmark Definition:**

The benchmark is designed to compare four different approaches for assigning values to an object property:

1. **Membership Check with `hasOwnProperty`**: This approach checks if the property exists on the object using `Object.prototype.hasOwnProperty.call(x, key)`.
2. **Self-Assignment (`??` Operator)**: This approach uses the nullish coalescing operator (`??`) to assign a default value of an empty array (`[]`) if the property is not present.
3. **Membership Check with `in`**: This approach checks if the property exists on the object using `(key in x)`.
4. **Null Check**: This approach checks if the property value is null, and assigns a new value if it is.

**Options Compared:**

The benchmark compares these four approaches to determine which one is the most efficient in terms of execution speed.

**Pros and Cons of Each Approach:**

1. **Membership Check with `hasOwnProperty`**:
	* Pros: This approach is widely supported and well-established.
	* Cons: It can be slower than other approaches, especially for large objects.
2. **Self-Assignment (`??` Operator)`:
	* Pros: This approach is concise and efficient, as it only requires a single operation.
	* Cons: The nullish coalescing operator was introduced in ES2019, so older browsers may not support it.
3. **Membership Check with `in`**:
	* Pros: This approach is similar to the first one but uses a different syntax.
	* Cons: It can be slower than other approaches for large objects due to the use of the `in` operator.
4. **Null Check**:
	* Pros: This approach is simple and efficient, as it only requires checking if the property value is null.
	* Cons: It may not work correctly if the property exists but has a non-null value.

**Library and Purpose:**

The benchmark uses the `Array.from()` method to create an array of keys, which is then used to iterate over the object properties. This approach allows for efficient iteration and comparison of the different assignment approaches.

**Special JS Feature/Syntax:**

The nullish coalescing operator (`??`) was introduced in ES2019 and is used in one of the benchmark test cases (self-assignment). While not all browsers support this feature, it provides a concise way to assign a default value if the property is not present.

Related benchmarks:

conditional self-assignment vs. membership check with in vs. membership check with hasOwnProperty vs. null check (version: 0)

Comparing performance of: hasOwnProperty membership check vs self-assignment vs in membership check vs null check

Created: one year ago by: Guest

Jump to the latest result

hasOwnProperty membership check

self-assignment

in membership check

null check

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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